Endoglin Antibodies

ABSTRACT

The present application relates to compositions of humanized and humanized/deimmunized anti-endoglin antibodies and antigen-binding fragments thereof. One aspect relates to antibodies having one or more modifications in at least one amino acid residue of at least one of the framework regions of the variable heavy chain, the variable light chain or both. Another aspect relates to antibodies which bind endoglin and inhibit angiogenesis. Another aspect relates to the deimmunization of humanized antibodies to reduce immunogenicity. Another aspect relates to the use of humanized and humanized/deimmunized antibodies which bind endoglin for the detection, diagnosis or treatment of a disease or condition associated with endoglin, angiogenesis or a combination thereof.

CROSS-REFERENCE

This application claims the benefit of U.S. Provisional Application No.61/247,290 filed Sep. 30, 2009 and U.S. Non-Provisional application Ser.No. 12/570,918 filed Sep. 30, 2009, the disclosures of all of which areherein incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

Endoglin, also known as, inter alia, CD105 or edg-1, is a type Ihomodimeric membrane glycoprotein which is expressed at high levels inproliferating vascular endothelial cells (Burrows et al., 1995, Clin.Cancer Res. 1:1623-1634). Thus, endoglin is primarily aproliferation-associated marker for endothelial cells undergoing activeangiogenesis. However, there is some expression of endoglin by thevascular endothelium of normal tissues (Burrows et al., supra; Wang etal., 1993, Int. J. Cancer 54:363-370). Human endoglin is known tospecifically bind transforming growth factor-β (TGF-β), and the deducedamino acid sequence of endoglin has strong homology to β-glycan, a typeof TGF-β receptor.

Endoglin (EDG) has been targeted in antibody-based methods of reducingtumor vasculature, as EDG is a proliferation-associated antigen onendothelial and leukemia cells. Its expression is up-regulated intumor-associated vascular endothelium, and EDG is essential forangiogenesis. Angiogenesis includes the formation of new capillary bloodvessels leading to neovascularization as well as the maintenance of theexisting vasculature. It is a complex process which includes a series ofsequential steps including endothelial cell-mediated degradation ofvascular basement membrane and interstitial matrices, migration ofendothelial cells, proliferation of endothelial cells, and formation ofcapillary loops by endothelial cells.

Several anti-endoglin antibodies, in particular anti-endoglin monoclonalantibodies (“mAb”), have been described. mAb SN6 is an antibodygenerated from immunization of mice with glycoprotein mixtures of cellmembranes of human leukemia cells (Haruta and Seon, 1986, Proc. Natl.Acad. Sci. 83:7898-7902). SN6 is a murine mAb that recognizes humanendoglin. mAb 44G4 is an antibody generated from immunization of micewith whole cell suspensions of human pre-B leukemia cells (Gougos andLetarte, 1988, J. Immunol. 141:1925-1933; 1990, J. Biol. Chem.265:8361-8364). 44G4 is also a murine mAb that recognizes humanendoglin. mAb MJ7/18 is an antibody generated from immunization of ratswith inflamed mouse skins (Ge and Butcher, 1994, supra). MJ7/18 is a mAbthat recognizes murine endoglin. mAb Tec-11 is an antibody generatedfrom immunization of mice with human umbilical vein endothelial cells(Burrows et al., 1995, Clin. Cancer Res. 1:1623-1634). Tec-11 is amurine mAb with reactivity restricted to human endoglin. Antibodiesagainst endoglin represent an important area for the development oftherapies for the treatment of a variety of diseases and conditionswhich involve, are influenced by, or affected by angiogenesis.

Angiogenesis is the physiological process by which new blood vesselsdevelop from pre-existing vessels (Varner, et al., Cell Adh. Commun.1995, 3:367-374; Blood, et al., Biochim. Biophys. Acta. 1990,1032:89-118; Weidner, et al., J. Natl. Cancer Inst. 1992, 84:1875-1887).Angiogenesis has been suggested to play a role in both normal andpathological processes. For example, angiogenic processes are involvedin the development of the vascular systems of animal organs and tissues.These processes are also involved in transitory phases of angiogenesis,for example during the menstrual cycle, in pregnancy, and in woundhealing. On the other hand, a number of diseases are known to beassociated with deregulated angiogenesis.

In certain pathological conditions, angiogenesis is stimulated as ameans to provide adequate blood and nutrient supply to the cells withinaffected tissue. Many of these pathological conditions involve aberrantcell proliferation and/or regulation. Therefore, inhibition ofangiogenesis is a potentially useful approach to treating diseases thatare characterized by new blood vessel development. For example,angiogenesis is involved in pathologic conditions including: variousforms of ocular and non-ocular diseases characterized byangiogenesis/neovascularization (e.g., macular degeneration, diabeticretinopathy), diabetic nephropathy, chronic inflammatory diseases (e.g.,IBD), rheumatoid arthritis, osteoarthritis, and various forms of cancer,solid tumors, and metastases and the like.

SUMMARY OF THE INVENTION

Provided herein are humanized antibodies or antigen-binding fragmentsthereof that bind to endoglin. Such antibodies have in vitro and in vivopurification, detection, diagnostic and therapeutic uses. Also providedherein are humanized antibodies or antigen-binding fragments thereofthat bind to one or more species or variants of endoglin and inhibitangiogenesis. Further provided herein are methods of treatingangiogenesis-associated diseases with humanized antibodies orantigen-binding fragments thereof that bind to endoglin.

The humanized antibodies and antigen-binding fragments which bindendoglin and are described herein can be used to treat or preventmacular degeneration, CNV, diabetic retinopathy, or proliferativevitreoretinopathy. Described herein are methods of treating orpreventing macular degeneration, CNV, diabetic retinopathy, orproliferative vitreoretinopathy via the administration of the antibodiesand antigen-binding fragments described herein. The humanized antibodiesand antigen-binding fragments which bind endoglin and are describedherein can also shrink blood vessels, inhibit endothelial cellproliferation associated with ocular disease, clear symptoms ofbleeding, treat cloudy vision, provide stasis of vision loss, and/orprevent leakage of blood vessels. The humanized antibodies andantigen-binding fragments described herein can also be used inmedicaments for the treatment of macular degeneration, CNV, diabeticretinopathy or proliferative vitreoretinopathy. The humanized antibodiesand antigen-binding fragments described herein can also be used inmedicaments for the treatment of cancer.

Provided herein are antibodies, or antigen-binding fragments thereof,having a heavy chain variable region having an amino acid sequence setforth as SEQ ID NO: 41 and a light chain variable region having an aminoacid sequence set forth as SEQ ID NO: 3.

Provided herein are antibodies, or antigen-binding fragments thereofthat bind endoglin, having comprising a light chain variable regionhaving an amino acid sequence set forth as SEQ ID NO: 3 and a heavychain variable region having an amino acid sequence set forth as SEQ IDNO: 41, wherein: said heavy chain variable region further comprises oneor more modifications selected from the group consisting of asubstitution of glycine (G) by alanine (A) at position 49; asubstitution of asparagine (N) by serine (S) at position 76; asubstitution of threonine (T) by arginine (R) at position 77; asubstitution of leucine (L) by valine (V) at position 78; a substitutionof asparagine (N) by isoleucine (I) at position 82a; a substitution ofvaline (V) by isoleucine (I) or leucine (L) at position 89; asubstitution of threonine (T) by arginine (R) or glycine (G) at position94; a substitution of leucine (L) by threonine (T) at position 108; asubstitution of valine (V) by leucine (L) at position 109; and asubstitution of serine (S) by alanine (A) at position 113 utilizing theKabat numbering system; and the light chain variable region furthercomprises one or more modifications selected from the group consistingof a substitution of aspartic acid (D) by glutamine (Q) at position 1; asubstitution of glutamine (Q) by valine (V) at position 3; asubstitution of methionine (M) by leucine (L) at position 4; asubstitution of threonine (T) by serine (S) at position 5; asubstitution of tyrosine (Y) by phenylalanine (F) at position 36; asubstitution of leucine (L) by proline (P) at position 46; asubstitution of leucine (L) by tryptophan (W) at position 47; asubstitution of serine (S) by valine (V) or alanine (A) at position 60;a substitution of aspartic acid (D) by serine (S) at position 70; asubstitution of phenylalanine (F) by tyrosine (Y) at position 71; asubstitution of glutamine (G) by alanine (A) at position 100; and asubstitution of isoleucine (I) by leucine (L) at position 106 utilizingthe Kabat numbering system

Provided herein are antibodies, or antigen-binding fragments thereofthat bind endoglin, having a heavy chain variable region and a lightchain variable region,

-   -   wherein said heavy chain variable region comprises:    -   (i) a CDR1 of SEQ ID NO: 66, a CDR2 of SEQ ID NO: 67, and a CDR3        of SEQ ID NO: 68;    -   (ii) a heavy chain FR1 having the amino acid sequence of SEQ ID        NO: 44 or the amino acid sequence of SEQ ID NO: 44 except for        one or more conservative substitutions;    -   (iii) a heavy chain FR2 having the amino acid sequence of SEQ ID        NO: 45 or the amino acid sequence of SEQ ID NO: 45 except for a        substitution of glycine (G) by alanine (A) at position 49        utilizing the Kabat numbering system; and    -   (iv) a heavy chain FR3 having the amino acid sequence of SEQ ID        NO: 47 or the amino acid sequence of SEQ ID NO: 47 except for        one or more substitutions selected from the group consisting of:        -   (a) a substitution of asparagine (N) by serine (S) at            position 76;        -   (b) a substitution of threonine (T) by arginine (R) at            position 77;        -   (c) a substitution of leucine (L) by valine (V) at position            78;        -   (d) a substitution of asparagine (N) by isoleucine (I) at            position 82a;        -   (e) a substitution of valine (V) by isoleucine (I) or            leucine (L) at position 89; and        -   (f) a substitution of threonine (T) by arginine (R) or            glycine (G) at position 94 utilizing the Kabat numbering            system; and    -   (v) a heavy chain FR4 having the amino acid sequence of SEQ ID        NO: 56 or the amino acid sequence of SEQ ID NO: 56 except for        one or more substitutions selected from the group consisting of:        -   (a) a substitution of leucine (L) by threonine (T) at            position 108;        -   (b) a substitution of valine (V) by leucine (L) at position            109; and        -   (c) a substitution of serine (S) by alanine (A) at position            113 utilizing the Kabat numbering system;    -   and said light chain variable region comprises:    -   (i) a CDR1 of SEQ ID NO: 63, a CDR2 of SEQ ID NO: 64, and a CDR3        of SEQ ID NO: 65;    -   (ii) a light chain FR1 having the amino acid sequence of SEQ ID        NO: 6 or the amino acid sequence of SEQ ID NO: 6 except for one        or more substitutions selected from the group consisting of:        -   (a) a substitution of aspartic acid (D) by glutamine (Q) at            position 1;        -   (b) a substitution of glutamine (Q) by valine (V) at            position 3;        -   (c) a substitution of methionine (M) by leucine (L) at            position 4; and        -   (d) a substitution of threonine (T) by serine (S) at            position 5; utilizing the Kabat numbering system; and    -   (iii) a light chain FR2 having the amino acid sequence of SEQ ID        NO: 20 or the amino acid sequence of SEQ ID NO: 20 except for        one or more substitutions selected from the group consisting of:        -   (a) a substitution of tyrosine (Y) by phenylalanine (F) at            position 36;        -   (b) a substitution of leucine (L) by proline (P) at position            46; and        -   (c) a substitution of leucine (L) by tryptophan (W) at            position 47 utilizing the Kabat numbering system; and    -   (iv) a light chain FR3 having the amino acid sequence of SEQ ID        NO: 28 or the amino acid sequence of SEQ ID NO: 28 except for        one or more substitutions selected from the group consisting of:        -   (a) a substitution of serine (S) by valine (V) or            alanine (A) at position 60;        -   (b) a substitution of aspartic acid (D) by serine (S) at            position 70; and        -   (b) a substitution of phenylalanine (F) by tyrosine (Y) at            position 71 utilizing the Kabat numbering system; and    -   (v) a light chain FR4 having the amino acid sequence of SEQ ID        NO: 35 or the amino acid sequence of SEQ ID NO: 35 except for        one or more substitutions selected from the group consisting of:        -   (a) a substitution of glycine (G) by alanine (A) at position            100; and        -   (b) a substitution of isoleucine (I) by leucine (L) at            position 106 utilizing the Kabat numbering system.

Provided herein is an antibody, or antigen-binding fragment thereof,comprising a heavy chain variable region having an amino acid sequenceset forth as SEQ ID NO: 42 and a light chain variable region having anamino acid sequence set forth as SEQ ID NO: 4.

Provided herein is an antibody, or antigen-binding fragment thereof,that binds endoglin, comprising a light chain variable region having anamino acid sequence set forth as SEQ ID NO: 4 and a heavy chain variableregion having an amino acid sequence set forth as SEQ ID NO: 42,wherein: said heavy chain variable region further comprises one or moremodifications selected from the group consisting of a substitution ofglycine (G) by alanine (A) at position 49; a substitution of asparagine(N) by serine (S) at position 76; a substitution of threonine (T) byarginine (R) at position 77; a substitution of leucine (L) by valine (V)at position 78; a substitution of asparagine (N) by isoleucine (I) atposition 82a; a substitution of valine (V) by isoleucine (I) or leucine(L) at position 89; a substitution of arginine (R) by threonine (T) orglycine (G) at position 94; a substitution of leucine (L) by threonine(T) at position 108; a substitution of valine (V) by leucine (L) atposition 109; and a substitution of serine (S) by alanine (A) atposition 113 utilizing the Kabat numbering system; and the light chainvariable region further comprises one or more modifications selectedfrom the group consisting of a substitution of aspartic acid (D) byglutamine (Q) at position 1; a substitution of glutamine (Q) by valine(V) at position 3; a substitution of methionine (M) by leucine (L) atposition 4; a substitution of threonine (T) by serine (S) at position 5;a substitution of tyrosine (Y) by phenylalanine (F) at position 36; asubstitution of proline (P) by leucine (L) at position 46; asubstitution of tryptophan (W) by leucine (L) at position 47; asubstitution of serine (S) by valine (V) or alanine (A) at position 60;a substitution of aspartic acid (D) by serine (S) at position 70; asubstitution of tyrosine (Y) by phenylalanine (F) at position 71; asubstitution of glutamine (G) by alanine (A) at position 100; and asubstitution of isoleucine (I) by leucine (L) at position 106 utilizingthe Kabat numbering system

Provided herein is an antibody, or antigen-binding fragment thereof,that binds endoglin, comprising a heavy chain variable region and alight chain variable region,

-   -   wherein said heavy chain variable region comprises:    -   (i) a CDR1 of SEQ ID NO: 66, a CDR2 of SEQ ID NO: 67, and a CDR3        of SEQ ID NO: 68;    -   (ii) a heavy chain FR1 having the amino acid sequence of SEQ ID        NO: 44 or the amino acid sequence of SEQ ID NO: 44 except for        one or more conservative substitutions;    -   (iii) a heavy chain FR2 having the amino acid sequence of SEQ ID        NO: 45 or the amino acid sequence of SEQ ID NO: 45 except for a        substitution of glycine (G) by alanine (A) at position 49        utilizing the Kabat numbering system; and    -   (iv) a heavy chain FR3 having the amino acid sequence of SEQ ID        NO: 47 or the amino acid sequence of SEQ ID NO: 47 except for        one or more substitutions selected from the group consisting of:        -   (a) a substitution of asparagine (N) by serine (S) at            position 76;        -   (b) a substitution of threonine (T) by arginine (R) at            position 77;        -   (c) a substitution of leucine (L) by valine (V) at position            78;        -   (d) a substitution of asparagine (N) by isoleucine at            position 82a;        -   (e) a substitution of valine (V) by isoleucine (I) or            leucine (L) at position 89; and        -   (f) a substitution of arginine (R) by threonine (T) or            glycine (G) at position 94 utilizing the Kabat numbering            system; and    -   (v) a heavy chain FR4 having the amino acid sequence of SEQ ID        NO: 56 or the amino acid sequence of SEQ ID NO: 56 except for        one or more substitutions selected from the group consisting of:

(a) a substitution of leucine (L) by threonine (T) at position 108;

(b) a substitution of valine (V) by leucine (L) at position 109; and

(c) a substitution of serine (S) by alanine (A) at position 113utilizing the Kabat numbering system;

-   -   and said light chain variable region comprises:    -   (i) a CDR1 of SEQ ID NO: 63, a CDR2 of SEQ ID NO: 64, and a CDR3        of SEQ ID NO: 65;    -   (ii) a light chain FR1 having the amino acid sequence of SEQ ID        NO: 6 or the amino acid sequence of SEQ ID NO: 6 except for one        or more substitutions selected from the group consisting of:        -   (a) a substitution of aspartic acid (D) by glutamine (Q) at            position 1;        -   (b) a substitution of glutamine (Q) by valine (V) at            position 3;        -   (c) a substitution of methionine (M) by leucine (L) at            position 4; and        -   (d) a substitution of threonine (T) by serine (S) at            position 5; utilizing the Kabat numbering system; and    -   (iii) a light chain FR2 having the amino acid sequence of SEQ ID        NO: 21 or the amino acid sequence of SEQ ID NO: 20 except for        one or more substitutions selected from the group consisting of:        -   (a) a substitution of tyrosine (Y) by phenylalanine (F) at            position 36;        -   (b) a substitution of proline (P) by leucine (L) at position            46; and        -   (c) a substitution of tryptophan (W) by leucine (L) at            position 47 utilizing the Kabat numbering system; and    -   (iv) a light chain FR3 having the amino acid sequence of SEQ ID        NO: 29 or the amino acid sequence of SEQ ID NO: 28 except for        one or more substitutions selected from the group consisting of:        -   (a) a substitution of serine (S) by valine (V) or            alanine (A) at position 60;        -   (b) a substitution of aspartic acid (D) by serine (S) at            position 70; and        -   (b) a substitution of tyrosine (Y) by phenylalanine (F) at            position 71 utilizing the Kabat numbering system; and    -   (v) a light chain FR4 having the amino acid sequence of SEQ ID        NO: 35 or the amino acid sequence of SEQ ID NO: 35 except for        one or more substitutions selected from the group consisting of:        -   (a) a substitution of glycine (G) by alanine (A) at position            100; and        -   (b) a substitution of isoleucine (I) by leucine (L) at            position 106 utilizing the Kabat numbering system.

Provided herein is an antibody, or antigen-binding fragment thereof,comprising a light chain variable region having an amino acid sequenceset forth as SEQ ID NO: 93 (VK1AA) and a heavy chain variable regionhaving an amino acid sequence set forth as SEQ ID NO: 89 (VH1A2).

Provided herein is an antibody, or antigen-binding fragment thereof,that binds endoglin, comprising a heavy chain variable region having anamino acid sequence set forth as SEQ ID NO: 89 and a light chainvariable region having an amino acid sequence set forth as SEQ ID NO:93, wherein:

(i) the heavy chain variable region further comprises one or moremodifications selected from the group consisting of a substitution ofglycine (G) by alanine (A) or serine (S) at position 49; a substitutionof alanine (A) by isoleucine (I) at position 51; a substitution oflysine (K) by arginine (R) or asparagine (O) at position 52b; asubstitution of leucine (L) by valine (V) at position 78 utilizing theKabat numbering system; and

(ii) the light chain variable region further comprises one or moremodifications selected from the group consisting of a substitution ofmethionine (M) by leucine (L) at position 4; a substitution of alanine(A) by valine (V) at position 19; a substitution of threonine (T) byserine (S) at position 22; a substitution of alanine (A) by isoleucine(I) at position 48; and a substitution of threonine (T) by serine (S) atposition 51 utilizing the Kabat numbering system.

Provided herein is an antibody, or antigen-binding fragment thereof, ofclaim 2 comprising a heavy chain variable region having an amino acidsequence set forth as SEQ ID NO: 88, 89, 90, 91 or 92; and a light chainvariable region having an amino acid sequence set forth as SEQ ID NO:93, 94, 95, 96, 97, 100, 102, or 103.

In one aspect, the antibodies and antigen-binding fragments describedherein are humanized and can be any isotype. Also encompassed herein areAVIMERs, diabodies, and heavy chain dimers (including camelids and sharkheavy chain constructs).

The terms “antigen-binding portion of an antibody,” “antigen-bindingfragment,” “antigen-binding domain,” “antibody fragment” or a“functional fragment of an antibody” are used interchangeably herein torefer to one or more fragments of an antibody that retain the ability tospecifically bind to an antigen. Non-limiting examples of antibodyfragments included within such terms include, but are not limited to,(i) a Fab fragment, a monovalent fragment consisting of the V_(L),V_(H), C_(L) and C_(H1) domains; (ii) a F(ab′)₂ fragment, a bivalentfragment containing two Fab fragments linked by a disulfide bridge atthe hinge region; (iii) a Fd fragment consisting of the V_(H) and C_(H1)domains; (iv) a Fv fragment containing the V_(L) and V_(H) domains of asingle arm of an antibody, (v) a dAb fragment (Ward et al., (1989)Nature 341:544 546), which containing a V_(H) domain; and (vi) anisolated CDR. Additionally included in this definition are “one-half”antibodies comprising a single heavy chain and a single light chain.Other forms of single chain antibodies, such as diabodies are alsoencompassed herein.

An antigen-binding fragment can be any of those described hereinincluding, but not limited to, a Fab fragment, a Fab′, a F(ab′)₂fragment, an Fv fragment (including non-covalently and covalently linkedFv fragments), an scFv fragment, a single chain binding polypeptide, anFd fragment, an Fv fragment or a dAb fragment. In one non-limitingembodiment, the antigen-binding fragment is a scFv which can,optionally, be further fused to a human Fc portion of an antibody.

In one non-limiting embodiment, the antibody, or antigen-bindingfragment thereof that binds endoglin comprises a heavy chain variableregion having an amino acid sequence set forth as SEQ ID NO: 41, 42, or43, and a light chain variable region having an amino acid sequence setforth as SEQ ID NO: 3, 4, or 5.

In another non-limiting embodiment, the antibody, or antigen-bindingfragment thereof comprises a heavy chain variable region having an aminoacid sequence set forth as SEQ ID NO: 41 and a light chain variableregion having an amino acid sequence set forth as SEQ ID NO: 3.

In another non-limiting embodiment, the antibody, or antigen-bindingfragment thereof comprises a heavy chain variable region having an aminoacid sequence set forth as SEQ ID NO: 41 and a light chain variableregion having an amino acid sequence set forth as SEQ ID NO: 4.

In another non-limiting embodiment, the antibody, or antigen-bindingfragment thereof comprises a comprising a heavy chain variable regionhaving an amino acid sequence set forth as SEQ ID NO: 41 and a lightchain variable region having an amino acid sequence set forth as SEQ IDNO: 5.

In another non-limiting embodiment, the antibody, or antigen-bindingfragment thereof comprises a heavy chain variable region having an aminoacid sequence set forth as SEQ ID NO: 42 and a light chain variableregion having an amino acid sequence set forth as SEQ ID NO: 3.

In another non-limiting embodiment, the antibody, or antigen-bindingfragment thereof comprises a heavy chain variable region having an aminoacid sequence set forth as SEQ ID NO: 42 and a light chain variableregion having an amino acid sequence set forth as SEQ ID NO: 4.

In another non-limiting embodiment, the antibody, or antigen-bindingfragment thereof comprises a heavy chain variable region having an aminoacid sequence set forth as SEQ ID NO: 42 and a light chain variableregion having an amino acid sequence set forth as SEQ ID NO: 5.

In another non-limiting embodiment, the antibody, or antigen-bindingfragment thereof comprises a heavy chain variable region having an aminoacid sequence set forth as SEQ ID NO: 43 and a light chain variableregion having an amino acid sequence set forth as SEQ ID NO: 3.

In another non-limiting embodiment, the antibody, or antigen-bindingfragment thereof comprises a heavy chain variable region having an aminoacid sequence set forth as SEQ ID NO: 43 and a light chain variableregion having an amino acid sequence set forth as SEQ ID NO: 4.

In another non-limiting embodiment, the antibody, or antigen-bindingfragment thereof comprises a heavy chain variable region having an aminoacid sequence set forth as SEQ ID NO: 43 and a light chain variableregion having an amino acid sequence set forth as SEQ ID NO: 5.

In yet another non-limiting embodiment, the antibody, or antigen-bindingfragment thereof heavy chain variable region further comprises one ormore modifications selected from the group consisting of: a substitutionof asparagine (N) by serine (S) at position 76; a substitution ofthreonine (T) by arginine (R) at position 77; a substitution ofasparagine (N) by isoleucine (I) at position 82a; a substitution ofvaline (V) by isoleucine (I) or leucine (L) at position 89; asubstitution of threonine (T) by glycine (G) at position 94; asubstitution of leucine (L) by threonine (T) at position 108; asubstitution of valine (V) by leucine (L) at position 109; and asubstitution of serine (S) by alanine (A) a position 113; and said lightchain variable region further comprises one or more modificationsselected from the group consisting of: a substitution of aspartic acid(D) by glutamine (Q) at position 1; a substitution of glutamine (Q) byvaline (V) at position 3; a substitution of threonine (T) by serine (S)at position 5; a substitution of tyrosine (Y) by phenylalanine (F) aposition 36; a substitution of serine (S) by valine (V) or alanine (A)at position 60; a substitution of aspartic acid (D) by serine (S) atposition 70; a substitution of glycine (G) by alanine (A) at position100, and a substitution of isoleucine (I) by leucine (L) at position 106utilizing the Kabat numbering system.

In one aspect, the antibodies and antigen-binding fragments describedherein can be modified. For example, in one embodiment, the compound canbe modified to alter a pharmacokinetic property of the compound such as,for example, in vivo stability, solubility, bioavailability orhalf-life. Such modifications include, but are not limited to,PEGylation and/or glycosylation.

The antibodies and antigen-binding fragments described herein can beformulated for rapid or extended delivery using conventional means. Inone non-limiting embodiment, rapid delivery is, for example, byintravenous injection. In another non-limiting embodiment, extendeddelivery is, for example, by subcutaneous deposition. In anothernon-limiting embodiment, delivery is achieved via administration byaerosol.

Provided herein are compositions of the antibodies and antigen-bindingfragments described herein and an acceptable carrier or excipient.

Provided herein are polynucleotides (nucleic acids) comprising anucleotide sequence encoding antibodies or antigen-binding fragmentsdescribed herein.

Antibodies and antigen-binding fragments thereof as described herein canbe used to treat various diseases and conditions associated withangiogenesis, e.g., various forms of ocular diseases characterized byangiogenesis/neovascularization (e.g., macular degeneration, diabeticretinopathy), diabetic nephropathy, chronic inflammatory diseases (e.g.,IBD), rheumatoid arthritis, osteoarthritis, and various forms of cancer,solid tumors, and metastases. Additionally, these antibodies andantigen-binding fragments thereof described herein can be used in theformulation of a medicament for the prophylaxis, treatment, or diagnosisof diseases and conditions associated with angiogenesis, e.g., variousforms of ocular and non-ocular diseases characterized byangiogenesis/neovascularization (e.g., macular degeneration, diabeticretinopathy), diabetic nephropathy, chronic inflammatory diseases (e.g.,IBD), rheumatoid arthritis, osteoarthritis, and various forms of cancer,solid tumors, and metastases.

Provided herein is a method for inducing a host immune response in apatient against endoglin, by administering to the patient a composition,where the composition comprises a humanized anti-endoglin antibody orantigen-binding fragment thereof that induces an effective host immuneresponse against the epitope specifically recognized by said antibody orfragment thereof.

The host immune response can be a humoral immune response or acell-mediated immune response. If the immune response is a humoralimmune response, it can be a protective antibody response that inhibitsangiogenesis, an angiogenesis-dependent disease or anangiogenesis-dependent disorder. Immune responses also include inductionor blockage of cell signaling pathways (e.g. Smad signaling). Theangiogenesis-dependent disease or disorder can be, for example, variousforms of ocular and non-ocular diseases characterized byangiogenesis/neovascularization (e.g., macular degeneration, diabeticretinopathy), diabetic nephropathy, chronic inflammatory diseases (e.g.,IBD), rheumatoid arthritis, osteoarthritis, various forms of cancer(primary tumors and metastases) and the like. In one embodiment, theprotective antibody response inhibits angiogenesis.

Provided herein is a method of affecting cell signaling pathwaysassociated with endoglin and angiogenesis. Angiogenic cells can becontacted (in vitro, in vivo or ex vivo) with an antibody orantigen-binding fragment thereof described herein in an amountsufficient to alter cell signaling pathways. In one non-limitingexample, in response to antibody binding, Smad 1, 5 and/or 8 signalingis inhibited by about 1.5 fold or more in angiogenic cells. In anothernon-limiting example, Smad 3 levels increase by about 1.5 fold or more,indicating that cells are returning to a quiescent state.

Provided herein is a method of inhibiting angiogenesis or anangiogenesis-dependent disease or disorder in a subject by administeringa composition provided herein to a patient. The angiogenesis-dependentdisease or disorder can be any of the following: various forms of ocularand non-ocular diseases characterized by angiogenesis/neovascularization(e.g., macular degeneration, diabetic retinopathy), diabeticnephropathy, chronic inflammatory diseases (e.g., IBD), rheumatoidarthritis, osteoarthritis, and various forms of cancer, solid tumors andmetastases. In one embodiment, inhibiting angiogenesis or anangiogenesis-dependent disease or disorder alleviates symptomsassociated with the disease or disorder. In another embodiment,inhibiting angiogenesis or an angiogenesis-dependent disease or disorderresults in decreased tumor size, prevention of tumor progression,decreased cell proliferation, increased apoptosis, or increased survivalof a patient. Inhibiting in angiogenesis can result in decreased tumorsize or prevent tumor progression. The method can further includesurgical removal of a cancer, and/or administration of on or moreadditional anti-cancer agents or treatments to a patient suffering fromcancer.

Provided herein is a method of preventing or treating a cancer ormetastasis in a subject by administering a composition provided herein.In one embodiment, administration of the pharmaceutical compositionprolongs life of the subject being treated. A cancer/tumor to be treatedincludes a solid tumor; a tumor can be a primary tumor or a metastatictumor. Exemplary solid tumors are of a tissue or organ selected fromamong skin, melanoma, lung, pancreas, breast, ovary, colon, rectum,stomach, thyroid, laryngeal, ovarian, prostate, colorectal, head, neck,eye, mouth, throat, esophagus, chest, bone, testicular, lymphoid,marrow, bone, sarcoma, renal, sweat gland, liver, kidney, brain, e.g.glioblastoma multiforme and the like tissues. In one non-limitingexample a solid tumor is a colon tumor, a breast tumor, a kidney tumor,a lung tumor, a prostate tumor, an ovarian tumor, or metastasis of anyof such tumors.

The method can further include surgical removal of the cancer and/oradministration of one or more anti-cancer agents. An anti-cancer agentcan be administered prior to, concomitant with, or subsequent to,administration of the pharmaceutical composition. An anti-cancer agentcan be administered within a week before the pharmaceutical composition,within a week after the pharmaceutical composition, or the anti-canceragent can be administered on the same day as the pharmaceuticalcomposition. If an anti-cancer agent is administered on the same day asthe pharmaceutical composition, administration can be concomitant.

Provided herein is a method for preventing or treating a cancer or ametastasis by surgical removal of the cancer/tumor and concurrentadministration of an anti-cancer agent or treatment and a compositionprovided herein to a subject.

Provided herein is a method of inhibiting angiogenesis by contacting acell or tissue with a therapeutically effective amount of an antibody orantigen-binding fragment thereof as described herein sufficient toinhibit angiogenesis.

Provided herein is a method of inhibiting cancer cell growth bycontacting a therapeutically effective amount of an antibody orantigen-binding fragment thereof as described herein sufficient toinhibit cancer cell growth or cause apoptosis of the cancer cell.

Provided herein is a method, comprising contacting a tissue with anantibody or antigen-binding fragment thereof as described herein,wherein contacting inhibits angiogenesis. The tissue can be a culturedtissue biopsy sample or can be present in a subject.

Provided herein is a method of preventing or treating a cellproliferative (e.g., angiogenic) disorder by administering to a subjecthaving or at risk of having a cell proliferative disorder an effectiveamount of a composition provided herein effective to treat the cellproliferative disorder. The cell proliferative disorder can be, forexample a benign or malignant solid or non-solid tumor and the tumor canbe metastatic or non-metastatic. The treatment can result in improvingthe subject's condition and can be assessed by determining if one ormore of the following factors has occurred: decreased cellproliferation, decreased numbers of cells, increased apoptosis, ordecreased survival of at least a portion of the cells comprising thecell proliferative disorder. One or more of these occurrences may, insome cases, result in partial or total elimination of the cancer andprolongation of survival of the patient. Optionally, the method canfurther include administering an anti-cancer agent or treatment to thesubject.

Provided herein is a method for treating diabetic retinopathy, maculardegeneration, choroidal neovascularization or neovascular glaucoma in apatient by administering to the patient a therapeutically effectiveamount of a composition provided herein. The treatment can result inimproving the subject's condition and can be assess by determining ifone or more of the following factors has occurred: decreased macularedema, decreased areas of CNV, or increased visual acuity.

In the methods provided herein, the subject can be a human or anon-human subject. Compositions and the anti-cancer agent or treatmentsprovided herein can be administered once or multiple times depending onthe health of the patient, the progression of the disease or condition,and the efficacy of the treatment. Adjustments to therapy and treatmentscan be made throughout the course of treatment.

Compositions can be administered locally, regionally or systemically,such as, for example, administration by subcutaneous, subcutaneous,intravitreal, intradermal, intravenous, intra-arterial, intraperitonealor intramuscular injection.

Additionally, humanized antibodies and antigen-binding fragmentsdescribed herein can also be used in combination with known therapiesand/or compounds for the treatment of macular degeneration, CNV,diabetic retinopathy or proliferative vitreoretinopathy. Examples ofsuch compounds include, but are not limited to, bevacizumab (AVASTIN®),ranibizumab (LUCENTIS®), aflibercept (VEGF-Trap), or Macugen. Inaddition to the modes of administration described herein, the humanizedanti-endoglin antibodies and antigen-binding fragments can beadministered via intravitreal routes. Non-limiting examples ofintravitreal modes of administration include intravitreal injection andthe use of intravitreal implants.

Another aspect is the treatment of a chronic inflammatory disease in asubject by administering a composition of an antibody or antigen-bindingfragment described herein. Non-limiting examples of chronic inflammatorydiseases include IBD, Crohn's disease, and ulcerative colitis.

Another aspect is the treatment of rheumatoid arthritis in a subject byadministering a composition of an antibody or antigen-binding fragmentdescribed herein.

Another aspect is the treatment of osteoarthritis in a subject byadministering a composition of an antibody or antigen-binding fragmentdescribed herein.

Treatment of a subject with rheumatoid arthritis and/or osteoarthritiscan be assessed by various means, including improvement in theappropriate categories of ACR scores as measured according to publishedguidelines.

Provided herein is a method of monitoring the efficacy of one or more ofany of the methods provided herein. Increased levels of soluble endoglinhave been correlated with decreased survival in cancer patients. Thus,in one aspect, levels of soluble endoglin can be monitored prior to andduring therapy. A decrease in the levels of soluble endoglin can,therefore, be one indication that a therapeutic regimen is effective intreating the patient.

One embodiment of the present invention contemplates the use of any ofthe compositions of the present invention to formulate a medicament fortreating a disorder of the present invention. Medicaments can beformulated based on the physical characteristics of the patient/subjectneeding treatment, and can be formulated in single or multipleformulations based on the stage of the cancerous tissue. Medicaments ofthe present invention can be packaged in a suitable pharmaceuticalpackage with appropriate labels for the distribution to hospitals andclinics wherein the label is for the indication of treating a disorderas described herein in a subject. Medicaments can be packaged as asingle or multiple units. Instructions for the dosage and administrationof the pharmaceutical compositions of the present invention can beincluded with the pharmaceutical packages.

Provided herein is a diagnostic method for providing a sample of cancercells of a solid tumor or plasma from a patient to be tested, detectingin the sample the expression of at least one gene or gene product chosenfrom a panel of genes or gene products whose expression has beencorrelated with sensitivity or resistance to an angiogenesis inhibitor,wherein the at least one gene or gene product is chosen from one or moregenes or gene products selected from the group consisting of VEGF, VEGFreceptor, HIF-1α, placental growth factor receptor, and CD105, andcomparing the level of expression of at least one gene or gene productdetected in the patient sample to a level of expression of at least onegene or gene product that has been correlated with sensitivity orresistance to the angiogenesis inhibitor. In one embodiment theangiogenesis inhibitor is chosen from VEGF receptor inhibitors, VEGFinhibitors, and endoglin inhibitors.

Provided herein is a kit for the detection of expression levels of genesthat have been correlated with sensitivity or resistance to anangiogenesis inhibitor in a sample of cancer cells or human plasma. Inone embodiment, one or more genes are selected from VEGF, VEGF receptor,HIF-1α, placental growth factor receptor, and endoglin.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference in its entiretyunless otherwise specifically noted. This application containsreferences to amino acid sequences which have been submittedconcurrently herewith as the sequence listing text file“35882-706-202-SeqList.txt”, file size 67,843 KiloBytes (KB), created onMar. 30, 2010. The aforementioned sequence listing is herebyincorporated by reference in its entirety pursuant to 37 C.F.R. §1.52(e)(5).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 provides a humanized O2-Vκ1-39 variable (V_(L)) light chainhaving the monoclonal murine chimeric TRC105 V_(L) CDRs (underlined)grafted between the framework regions (FRs) 1-3 of the human sequenceO2-Vκ1-39 and a framework region 4 from the human Jκ4 sequence (SEQ IDNO: 4) (all in bold). Variations that can be made to the human FRs areindicated at positions 1, 3, 4, 5, 36, 46, 47, 60, 70, 71, 100, and 106of the sequence (sequence disclosed at SEQ ID NO: 86) utilizing theKabat numbering system (shown in italics beneath the humanizedsequence).

FIG. 2 provides a humanized VH3-15 variable (V_(H)) heavy chain havingthe monoclonal murine monoclonal murine chimeric TRC105 V_(H) CDRs(underlined) grafted between the framework regions (FRs) 1-3 of thehuman sequence VH3-15 and a framework region 4 from the human JH4sequence (SEQ ID NO: 42) (all in bold). One or more variations that canbe made to the human FRs are indicated at positions 49, 76, 77, 78, 82a,89, 94, 108, 109, and 113 of the sequence (sequence disclosed at SEQ IDNO: 87) utilizing the Kabat numbering system (shown in italics beneaththe humanized sequence).

FIG. 3 provides diagram of the TGF-β/ALK5 signaling pathway. TheTGF-β/ALK5 pathway (A) leads to inhibition of cell proliferation andmigration. The TGF-β/ALK1 pathway (B) induces endothelial cellproliferation and migration and requires CD105 (endoglin) for ALK1signaling. The dotted lines indicate inactive or blocked pathways. Thebolded arrow indicates stimulation of a signaling pathway.

FIG. 4 provides an amino acid sequence alignment of exemplary mouse andhumanized VK chains (SEQ ID NOS 1-5, respectively, in order ofappearance) and V_(H) chains (SEQ ID NOS 39-43, respectively, in orderof appearance) produced according the invention described herein.

FIG. 5 provides an amino acid sequence alignment of exemplary mouse andsuper-humanized VK chains (SEQ ID NOS 1 and 69-72, respectively, inorder of appearance) and V_(H) chains (SEQ ID NOS 39 and 73-75,respectively, in order of appearance) produced according the inventiondescribed herein.

FIG. 6 provides an amino acid sequence alignment and comparison ofexemplary mouse and humanized and super-humanized VK chains (SEQ ID NOS1, 3 and 70, respectively, in order of appearance) and V_(H) chains (SEQID NOS 39, 41 and 74, respectively, in order of appearance) producedaccording the invention described herein.

FIG. 7 illustrates binding of humanized variant constructs to endoglinin a competition ELISA assay.

FIG. 8. Anti-CD105 competition ELISA with humanized andhumanized/deimmunized antibodies. Varying concentrations of eachantibody were mixed with a fixed concentration of biotinylated referenceanti-CD105 antibody (6.25 ng/ml) and bound to CD105 (100 ng/ml) capturedon a Nunc MaxiSorp plate. Binding was detected via streptavidin-HRP andTMB substrate. Absorbance (OD) at 450 nm was measured on a plate readerand this was plotted against the test antibody concentration.

FIG. 9 illustrates binding assay data for variant VK1AAVH1A plus VK2containing controls.

FIG. 10 illustrates binding assay data for chimeric compared toVK1AAVH1A2 and VK2AAVH1A2.

FIG. 11 illustrates binding assay data for chimeric compared toVK2AAVH1Q.

FIG. 12 illustrates binding assay data for chimeric compared toVK2AAVH1R.

FIG. 13 illustrates binding assay data for chimeric compared toVK1AAVH1A2.

FIG. 14 illustrates binding assay data for chimeric compared toVK1AAVH1Q.

FIG. 15 illustrates binding assay data for chimeric compared toVK1AAVH1R.

FIG. 16 illustrates binding assay data for chimeric compared toVK2AAVH1A2.

FIG. 17 illustrates the lead humanized deimmunized heavy chain variableregion with CDRs in bold and underlined (sequence disclosed at SEQ IDNO: 89). Variations that can be made are indicated at the identifiedpositions of the sequence utilizing the Kabat numbering system (sequencedisclosed at SEQ ID NO: 116) (shown in italics beneath the humanizedsequence). Variations may be made as a single mutation or as more thanone mutation, and variations can be made with mutations in anycombination.

FIG. 18 illustrates the lead humanized deimmunized light chain variableregion with CDRs in bold and underlined (sequence disclosed at SEQ IDNO: 93). Variations that can be made are indicated at the identifiedpositions of the sequence utilizing the Kabat numbering system (sequencedisclosed at SEQ ID NO: 117) (shown in italics beneath the humanizedsequence). Variations may be made as a single mutation or as more thanone mutation, and variations can be made with mutations in anycombination.

FIG. 19 illustrates Analysis of the regions of the heavy chain (SEQ IDNO: 41) using iTope™. Peptides spanning the entire sequence were testedas 9mer peptides in one amino acid increments. The predicted binding ofeach residue as the p1 anchor of a core 9mer peptide to MHC class IIalleles is indicated by a “O” if the binding score was 0.55-0.6 and by a“X” if the binding score was >0.6. Regions containing potentiallyimmunogenic peptides are indicated in the “iTope” column, dark greyindicates promiscuous high affinity MHC class II binding peptides, lightgrey indicates promiscuous moderate affinity MHC class II bindingpeptides. The numbers of MHC class II alleles predicted to bind areshown in the “total” and “high affinity” columns. Potential p1 anchorresidues identified as germline sequences are shown in reverse type inthe “Sequence” column.

FIG. 20 illustrates analysis of the variant regions of variants of theheavy chain (SEQ ID NO: 118) using iTope™. Peptides spanning the entiresequence were tested as 9mer peptides in one amino acid increments. Thepredicted binding of each residue as the p1 anchor of a core 9merpeptide to MHC class II alleles is indicated by a “O” if the bindingscore was 0.55-0.6 and by a “X” if the binding score was >0.6. Regionscontaining potentially immunogenic peptides are indicated in the “iTope”column, dark grey indicates promiscuous high affinity MHC class IIbinding peptides, light grey indicates promiscuous moderate affinity MHCclass II binding peptides. The numbers of MHC class II alleles predictedto bind are shown in the “total” and “high affinity” columns and thedifference to binding is shown. Potential p1 anchor residues identifiedas germline sequences are shown in reverse type in the “Sequence” columnand the amino acid differences in the variants are boxed.

FIG. 21 illustrates analysis of the regions of the light chain (SEQ IDNO: 3) using iTope™. Peptides spanning the entire sequence were testedas 9mer peptides in one amino acid increments. The predicted binding ofeach residue as the p1 anchor of a core 9mer peptide to MHC class IIalleles is indicated by a “O” if the binding score was 0.55-0.6 and by a“X” if the binding score was >0.6. Regions containing potentiallyimmunogenic peptides are indicated in the “iTope” column, dark greyindicates promiscuous high affinity MHC class II binding peptides, lightgrey indicates promiscuous moderate affinity MHC class II bindingpeptides. The numbers of MHC class II alleles predicted to bind areshown in the “total” and “high affinity” columns. Potential p1 anchorresidues identified as germline sequences are shown in reverse type inthe “Sequence” column.

FIG. 22 illustrates analysis of the variant regions of the light chain(SEQ ID NO: 101) using iTope™. Peptides spanning the entire sequencewere tested as 9mer peptides in one amino acid increments. The predictedbinding of each residue as the p1 anchor of a core 9mer peptide to MHCclass II alleles is indicated by a “O” if the binding score was 0.55-0.6and by a “X” if the binding score was >0.6. Regions containingpotentially immunogenic peptides are indicated in the “iTope” column,dark grey indicates promiscuous high affinity MHC class II bindingpeptides, light grey indicates promiscuous moderate affinity MHC classII binding peptides. The numbers of MHC class II alleles predicted tobind are shown in the “total” and “high affinity” columns and thedifference to binding is shown. Potential p1 anchor residues identifiedas germline sequences are shown in reverse type in the “Sequence” columnand the amino acid differences in the variants are boxed.

FIG. 23 illustrates the frequency of MHC Class II allotypes in the worldpopulation and the study population.

FIG. 24 Chimeric anti-endoglin antibody, humanized anti-endoglinantibody VK1VH1 and humanized/deimmunized anti-endoglin antibodyVK1AAVH1A2 were tested in EpiScreen™ time course T cell assays usingPBMC from 20 donors. Bulk cultures of PBMC incubated with testantibodies were sampled on days 5, 6, 7 and 8, and pulsed with³H-Thymidine. Cells were harvested and incorporation of radioactivitymeasured by scintillation counting. Results for each triplicate samplewere averaged and normalized by conversion to Stimulation Index (SI).The SI for each time point with each donor is shown above for thechimeric antibody TRC105 (FIG. 24A), VK1VH1 (FIG. 24B) and VK1AAVH1A2(FIG. 24C). The cut-off for determining positive responses with an SI≧2is highlighted by the dotted line and significant responses (p<0.05 in astudent's t-test) are indicated (*).

DETAILED DESCRIPTION OF THE INVENTION

It is to be understood that this application is not limited toparticular formulations or process parameters, as these may, of course,vary. It is also to be understood that the terminology used herein isfor the purpose of describing particular embodiments only, and is notintended to be limiting. Further, it is understood that a number ofmethods and materials similar or equivalent to those described hereincan be used in the practice of the present inventions.

In accordance with the present application, there may be employedconventional molecular biology, microbiology, and recombinant DNAtechniques within the skill of the art. Such techniques are explainedfully in the literature. See, e.g., Sambrook et al, “Molecular Cloning:A Laboratory Manual” (1989); “Current Protocols in Molecular Biology”Volumes I-III [Ausubel, R. M., ed. (1994)]; “Cell Biology: A LaboratoryHandbook” Volumes I-III [J. E. Celis, ed. (1994))]; “Current Protocolsin Immunology” Volumes I-III [Coligan, J. E., ed. (1994)];“Oligonucleotide Synthesis” (M. J. Gait ed. 1984); “Nucleic AcidHybridization” [B. D. Hames & S. J. Higgins eds. (1985)]; “TranscriptionAnd Translation” [B. D. Hames & S. J. Higgins, eds. (1984)]; “AnimalCell Culture” [R. I. Freshney, ed. (1986)]; “Immobilized Cells AndEnzymes” [IRL Press, (1986)]; B. Perbal, “A Practical Guide To MolecularCloning” (1984), each of which is specifically incorporated herein byreference in its entirety.

Murine monoclonal antibodies (mAbs) have been raised against endoglinwhich modulate endoglin activity and thereby inhibit angiogenesis and/orinhibit vasodilation of small blood vessels. These murine antibodies aredescribed in U.S. Pat. Nos. 5,928,641, 6,200,566, 6,190,660, and7,097,836 which are hereby incorporated in their entirety. Additionally,the ex vivo and in vivo efficiency of a number of these antibodies hasbeen demonstrated; these monoclonal antibodies that bind endoglin are ofinterest as endoglin modulating compounds. Therapeutic use of thesemurine antibodies is not feasible, however, as their administration hasa number of limitations, including immunogenicity in, for example, theform of human anti-mouse antibodies (HAMA). Humanized antibodies aremade to address these reactions.

Humanized antibodies that bind endoglin are described herein thatexhibit reduced immunogenicity while maintaining and/or improving theirspecificity. Additionally, to address problems associated with murineantibodies, humanized antibodies that bind endoglin and decrease and/orinhibit angiogenesis are described herein that exhibit reducedimmunogenicity while maintaining and/or improving their specificity.These humanized endoglin antibodies are useful for the diagnosis andtreatment of various conditions and diseases as well as for purificationand detection of endoglin.

I. Anti-Endoglin Antibodies

Provided herein are humanized antibodies, and antigen-binding fragmentsthereof that bind endoglin. Endoglin can be found on cells that compriseand support existing vasculature as well as cells that are promoting thegrowth of, and become part of, new vasculature. These antibodies andantigen-binding fragments can bind endoglin and thereby inhibitangiogenesis, inhibit the existing vasculature or the maintenance of theexisting vasculature, and/or inhibit small vessel dilation. Hereinafter,a reference to the terms “antibody” or “antibodies” are to be consideredinclusive of any of the antigen-binding fragments described herein andthe terms are to be interchangeable where applicable. In addition totheir use for purification of endoglin, these antibodies are useful forpurification, detection and diagnostic purposes as well as therapeuticpurposes. The antibodies provided herein can be used for the formulationof medicaments for the treatment a variety of conditions and diseases,methods to treat said conditions and diseases and methods of detectionor diagnosis. As used herein, angiogenesis is inclusive of the growthand/or development of new blood vessels (also referred to asneovascularization), dilation of the small vessels, excessive orprolonged vascular growth, and maintenance of the existing vasculature.Angiogenesis conditions and diseases refers to those diseases andconditions related to, caused by, or associated with angiogenesis.Non-limiting examples of such diseases include, for example, variousforms of ocular diseases characterized byangiogenesis/neovascularization (e.g., macular degeneration, CNV,diabetic retinopathy), diabetic nephropathy, chronic inflammatorydiseases (e.g., IBD), rheumatoid arthritis, osteoarthritis, and variousforms of cancer (primary tumors and metastases).

A. Antibody Terminology

As used herein, the term “antibody” refers to an immunoglobulin (Ig)whether natural or partly or wholly synthetically produced. The termalso covers any polypeptide or protein having a binding domain which is,or is homologous to, an antigen-binding domain. The term furtherincludes “antigen-binding fragments” and other interchangeable terms forsimilar binding fragments such as described below. Complementaritydetermining region (CDR) grafted antibodies and other humanizedantibodies (including CDR modifications and framework regionmodifications) are also contemplated by this term.

Native antibodies and native immunoglobulins are usuallyheterotetrameric glycoproteins of about 150,000 Daltons, composed of twoidentical light (L) chains and two identical heavy (H) chains. Eachlight chain is typically linked to a heavy chain by one covalentdisulfide bond, while the number of disulfide linkages varies among theheavy chains of different immunoglobulin isotypes. Each heavy and lightchain also has regularly spaced intrachain disulfide bridges. Each heavychain has at one end a variable domain (“V_(H)”) followed by a number ofconstant domains (“C_(H)”). Each light chain has a variable domain atone end (“V_(L)”) and a constant domain (“C_(L)”) at its other end; theconstant domain of the light chain is aligned with the first constantdomain of the heavy chain, and the light-chain variable domain isaligned with the variable domain of the heavy chain. Particular aminoacid residues are believed to form an interface between the light- andheavy-chain variable domains.

The terms “synthetic polynucleotide,” “synthetic gene” or “syntheticpolypeptide,” as used herein, mean that the corresponding polynucleotidesequence or portion thereof, or amino acid sequence or portion thereof,is derived, from a sequence that has been designed, or synthesized denovo, or modified, compared to an equivalent naturally-occurringsequence. Synthetic polynucleotides (antibodies or antigen bindingfragments) or synthetic genes can be prepared by methods known in theart, including but not limited to, the chemical synthesis of nucleicacid or amino acid sequences. Synthetic genes are typically differentfrom naturally-occurring genes, either at the amino acid, orpolynucleotide level, (or both) and are typically located within thecontext of synthetic expression control sequences. For example,synthetic gene sequences can include amino acid, or polynucleotide,sequences that have been changed, for example, by the replacement,deletion, or addition, of one or more, amino acids, or nucleotides,thereby providing an antibody amino acid sequence, or a polynucleotidecoding sequence that is different from the source sequence. Syntheticgene polynucleotide sequences, may not necessarily encode proteins withdifferent amino acids, compared to the natural gene; for example, theycan also encompass synthetic polynucleotide sequences that incorporatedifferent codons but which encode the same amino acid (i.e., thenucleotide changes represent silent mutations at the amino acid level).

With respect to antibodies, the term “variable domain” refers to thevariable domains of antibodies that are used in the binding andspecificity of each particular antibody for its particular antigen.However, the variability is not evenly distributed throughout thevariable domains of antibodies. Rather, it is concentrated in threesegments called hypervariable regions (also known as CDRs) in both thelight chain and the heavy chain variable domains. More highly conservedportions of variable domains are called the “framework regions” or“FRs.” The variable domains of unmodified heavy and light chains eachcontain four FRs (FR1, FR2, FR3 and FR4), largely adopting a β-sheetconfiguration interspersed with three CDRs which form loops connectingand, in some cases, part of the n-sheet structure. The CDRs in eachchain are held together in close proximity by the FRs and, with the CDRsfrom the other chain, contribute to the formation of the antigen-bindingsite of antibodies (see Kabat et al., Sequences of Proteins ofImmunological Interest, 5th Ed. Public Health Service, NationalInstitutes of Health, Bethesda, Md. (1991), pages 647-669).

The terms “hypervariable region” and “CDR” when used herein, refer tothe amino acid residues of an antibody which are responsible forantigen-binding. The CDRs comprise amino acid residues from threesequence regions which bind in a complementary manner to an antigen andare known as CDR1, CDR2, and CDR3 for each of the V_(H) and V_(I),chains. In the light chain variable domain, the CDRs typicallycorrespond to approximately residues 24-34 (CDRL1), 50-56 (CDRL2) and89-97 (CDRL3), and in the heavy chain variable domain the CDRs typicallycorrespond to approximately residues 31-35 (CDRH1), 50-65 (CDRH2) and95-102 (CDRH3) according to Kabat et al., Sequences of Proteins ofImmunological Interest, 5th Ed. Public Health Service, NationalInstitutes of Health, Bethesda, Md. (1991)). It is understood that theCDRs of different antibodies may contain insertions, thus the amino acidnumbering may differ. The Kabat numbering system accounts for suchinsertions with a numbering scheme that utilizes letters attached tospecific residues (e.g., 27A, 27B, 27C, 27D, 27E, and 27F of CDRL1 inthe light chain) to reflect any insertions in the numberings betweendifferent antibodies. Alternatively, in the light chain variable domain,the CDRs typically correspond to approximately residues 26-32 (CDRL1),50-52 (CDRL2) and 91-96 (CDRL3), and in the heavy chain variable domain,the CDRs typically correspond to approximately residues 26-32 (CDRH1),53-55 (CDRH2) and 96-101 (CDRH3) according to Chothia and Lesk, J. Mol.Biol., 196: 901-917 (1987)).

As used herein, “framework region” or “FR” refers to framework aminoacid residues that form a part of the antigen binding pocket or groove.In some embodiments, the framework residues form a loop that is a partof the antigen binding pocket or groove and the amino acids residues inthe loop may or may not contact the antigen. Framework regions generallycomprise the regions between the CDRs. In the light chain variabledomain, the FRs typically correspond to approximately residues 0-23(FRL1), 35-49 (FRL2), 57-88 (FRL3), and 98-109 and in the heavy chainvariable domain the FRs typically correspond to approximately residues0-30 (FRH1), 36-49 (FRH2), 66-94 (FRH3), and 103-133 according to Kabatet al., Sequences of Proteins of Immunological Interest, 5th Ed. PublicHealth Service, National Institutes of Health, Bethesda, Md. (1991)). Asdiscussed above with the Kabat numbering for the light chain, the heavychain too accounts for insertions in a similar manner (e.g., 35A, 35B ofCDRH1 in the heavy chain). Alternatively, in the light chain variabledomain, the FRs typically correspond to approximately residues 0-25(FRL1), 33-49 (FRL2) 53-90 (FRL3), and 97-109 (FRL4), and in the heavychain variable domain, the FRs typically correspond to approximatelyresidues 0-25 (FRH1), 33-52 (FRH2), 56-95 (FRH3), and 102-113 (FRH4)according to Chothia and Lesk, J. Mol. Biol., 196: 901-917 (1987)).

The loop amino acids of a FR can be assessed and determined byinspection of the three-dimensional structure of an antibody heavy chainand/or antibody light chain. The three-dimensional structure can beanalyzed for solvent accessible amino acid positions as such positionsare likely to form a loop and/or provide antigen contact in an antibodyvariable domain. Some of the solvent accessible positions can tolerateamino acid sequence diversity and others (e.g., structural positions)are, generally, less diversified. The three dimensional structure of theantibody variable domain can be derived from a crystal structure orprotein modeling.

Constant domains (Fc) of antibodies are not involved directly in bindingan antibody to an antigen but, rather; exhibit various effectorfunctions, such as participation of the antibody in antibody-dependentcellular toxicity via interactions with, for example, Fc receptors(FcR). Fc domains can also increase bioavailability of an antibody incirculation following administration to a patient.

Depending on the amino acid sequence of the constant domain of theirheavy chains, immunoglobulins can be assigned to different classes.There are five major classes of immunoglobulins: IgA, IgD, IgE, IgG, andIgM, and several of these can be further divided into subclasses(isotypes), e.g., IgG1, IgG2, IgG3, IgG4, IgA1, and IgA2. Theheavy-chain constant domains (Fc) that correspond to the differentclasses of immunoglobulins are called α, δ, ε, γ, and μ respectively.The subunit structures and three-dimensional configurations of differentclasses of immunoglobulins are well known.

The “light chains” of antibodies (immunoglobulins) from any vertebratespecies can be assigned to one of two clearly distinct types, calledkappa or (“κ” or “K”) and lambda or (“λ”), based on the amino acidsequences of their constant domains.

The terms “antigen-binding portion of an antibody,” “antigen-bindingfragment,” “antigen-binding domain,” “antibody fragment” or a“functional fragment of an antibody” are used interchangeably herein torefer to one or more fragments of an antibody that retain the ability tospecifically bind to an antigen. Non-limiting examples of antibodyfragments included within such terms include, but are not limited to,(i) a Fab fragment, a monovalent fragment consisting of the V_(L),V_(H), C_(L) and C_(H1) domains; (ii) a F(ab′)₂ fragment, a bivalentfragment containing two Fab fragments linked by a disulfide bridge atthe hinge region; (iii) a Fd fragment consisting of the V_(H) and C_(H1)domains; (iv) a Fv fragment containing the V_(L) and V_(H) domains of asingle arm of an antibody, (v) a dAb fragment (Ward et al., (1989)Nature 341:544 546), which containing a V_(H) domain; and (vi) anisolated CDR. Additionally included in this definition are “one-half”antibodies comprising a single heavy chain and a single light chain.Other forms of single chain antibodies, such as diabodies are alsoencompassed herein.

“F(ab′)₂” and “Fab′” moieties can be produced by treating an Ig with aprotease such as pepsin and papain, and include antibody fragmentsgenerated by digesting immunoglobulin near the disulfide bonds existingbetween the hinge regions in each of the two heavy chains. For example,papain cleaves IgG upstream of the disulfide bonds existing between thehinge regions in each of the two heavy chains to generate two homologousantibody fragments in which an light chain composed of V_(L) and C_(L)(light chain constant region), and a heavy chain fragment composed ofV_(H) and C_(Hγ1) (γ1l) region in the constant region of the heavychain) are connected at their C terminal regions through a disulfidebond. Each of these two homologous antibody fragments is called Fab′.Pepsin also cleaves IgG downstream of the disulfide bonds existingbetween the hinge regions in each of the two heavy chains to generate anantibody fragment slightly larger than the fragment in which the twoabove-mentioned Fab′ are connected at the hinge region. This antibodyfragment is called F(ab′)₂.

The Fab fragment also contains the constant domain of the light chainand the first constant domain (C_(H)1) of the heavy chain. Fab′fragments differ from Fab fragments by the addition of a few residues atthe carboxyl terminus of the heavy chain C_(H)1 domain including one ormore cysteine(s) from the antibody hinge region. Fab′-SH is thedesignation herein for Fab′ in which the cysteine residue(s) of theconstant domains bear a free thiol group. F(ab)₂ antibody fragmentsoriginally were produced as pairs of Fab′ fragments which have hingecysteines between them. Other chemical couplings of antibody fragmentsare also known.

“Fv” refers to an antibody fragment which contains a completeantigen-recognition and antigen-binding site. This region consists of adimer of one heavy chain and one light chain variable domain in tight,non-covalent or covalent association (disulfide linked Fv's have beendescribed in the art, Reiter et al. (1996) Nature Biotechnology14:1239-1245). It is in this configuration that the three CDRs of eachvariable domain interact to define an antigen-binding site on thesurface of the V_(H)-V_(L) dimer. Collectively, a combination of one ormore of the CDRs from each of the V_(H) and V_(L) chains conferantigen-binding specificity to the antibody. For example, it would beunderstood that, for example, the CDRH3 and CDRL3 could be sufficient toconfer antigen-binding specificity to an antibody when transferred toV_(H) and V_(L) chains of a recipient antibody or antigen-bindingfragment thereof and this combination of CDRs can be tested for binding,affinity, etc. using any of the techniques described herein. Even asingle variable domain (or half of an Fv comprising only three CDRsspecific for an antigen) has the ability to recognize and bind antigen,although likely at a lower affinity than when combined with a secondvariable domain. Furthermore, although the two domains of a Fv fragment(V_(L) and V_(H)), are coded for by separate genes, they can be joinedusing recombinant methods by a synthetic linker that enables them to bemade as a single protein chain in which the V_(L) and V_(H) regions pairto form monovalent molecules (known as single chain Fv (scFv); Bird etal. (1988) Science 242:423-426; Huston et al. (1988) Proc. Natl. Acad.Sci. USA 85:5879-5883; and Osbourn et al. (1998) Nat. Biotechnol.16:778). Such scFvs are also intended to be encompassed within the term“antigen-binding portion” of an antibody. Any V_(H) and V_(L) sequencesof specific scFv can be linked to an Fc region cDNA or genomicsequences, in order to generate expression vectors encoding complete Ig(e.g., IgG) molecules or other isotypes. V_(H) and V_(L) can also beused in the generation of Fab, Fv or other fragments of Igs using eitherprotein chemistry or recombinant DNA technology.

“Single-chain Fv” or “sFv” antibody fragments comprise the V_(H) andV_(L) domains of an antibody, wherein these domains are present in asingle polypeptide chain. In some embodiments, the Fv polypeptidefurther comprises a polypeptide linker between the V_(H) and V_(L)domains which enables the sFv to form the desired structure for antigenbinding. For a review of sFvs see, e.g., Pluckthun in The Pharmacologyof Monoclonal Antibodies, Vol. 113, Rosenburg and Moore eds.Springer-Verlag, New York, pp. 269-315 (1994).

The term “AVIMER™” refers to a class of therapeutic proteins of humanorigin, which are unrelated to antibodies and antibody fragments, andare composed of several modular and reusable binding domains, referredto as A-domains (also referred to as class A module, complement typerepeat, or LDL-receptor class A domain). They were developed from humanextracellular receptor domains by in vitro exon shuffling and phagedisplay (Silverman et al., 2005, Nat. Biotechnol. 23:1493-1494;Silverman et al., 2006, Nat. Biotechnol. 24:220). The resulting proteinscan contain multiple independent binding domains that can exhibitimproved affinity (in some cases, sub-nanomolar) and specificitycompared with single-epitope binding proteins. See, for example, U.S.Patent Application Publ. Nos. 2005/0221384, 2005/0164301, 2005/0053973and 2005/0089932, 2005/0048512, and 2004/0175756, each of which ishereby incorporated by reference herein in its entirety.

Each of the known 217 human A-domains comprises ˜35 amino acids (˜4kDa); and these domains are separated by linkers that average five aminoacids in length. Native A-domains fold quickly and efficiently to auniform, stable structure mediated primarily by calcium binding anddisulfide formation. A conserved scaffold motif of only 12 amino acidsis required for this common structure. The end result is a singleprotein chain containing multiple domains, each of which represents aseparate function. Each domain of the proteins binds independently andthe energetic contributions of each domain are additive. These proteinswere called “AVIMERs™” from avidity multimers.

The term “diabodies” refers to small antibody fragments with twoantigen-binding sites, which fragments comprise a heavy chain variabledomain (V_(H)) connected to a light chain variable domain (V_(L)) in thesame polypeptide chain (V_(H)-V_(L)). By using a linker that is tooshort to allow pairing between the two domains on the same chain, thedomains are forced to pair with the complementary domains of anotherchain and create two antigen-binding sites. Diabodies are described morefully in, for example, EP 404,097; WO 93/11161; and Hollinger et al.,Proc. Natl. Acad. Sci. USA 90:6444 6448 (1993).

Antigen-binding polypeptides also include heavy chain dimers such as,for example, antibodies from camelids and sharks. Camelid and sharkantibodies comprise a homodimeric pair of two chains of V-like andC-like domains (neither has a light chain). Since the V_(H) region of aheavy chain dimer IgG in a camelid does not have to make hydrophobicinteractions with a light chain, the region in the heavy chain thatnormally contacts a light chain is changed to hydrophilic amino acidresidues in a camelid. V_(H) domains of heavy-chain dimer IgGs arecalled V_(HH) domains. Shark Ig-NARs comprise a homodimer of onevariable domain (termed a V-NAR domain) and five C-like constant domains(C-NAR domains). In camelids, the diversity of antibody repertoire isdetermined by the CDRs 1, 2, and 3 in the V_(H) or V_(HH) regions. TheCDR3 in the camel V_(HH) region is characterized by its relatively longlength, averaging 16 amino acids (Muyldermans et al., 1994, ProteinEngineering 7(9): 1129). This is in contrast to CDR3 regions ofantibodies of many other species. For example, the CDR3 of mouse V_(H)has an average of 9 amino acids. Libraries of camelid-derived antibodyvariable regions, which maintain the in vivo diversity of the variableregions of a camelid, can be made by, for example, the methods disclosedin U.S. Patent Application Ser. No. 20050037421.

“Humanized” forms of non-human (e.g., murine) antibodies includechimeric antibodies which contain minimal sequence derived from anon-human Ig. For the most part, humanized antibodies are human Igs(recipient antibody) in which one or more of the CDRs of the recipientare replaced by CDRs from a non-human species antibody (donor antibody)such as mouse, rat, rabbit or non-human primate having the desiredspecificity, affinity and binding function. In some instances, one ormore FR amino acid residues of the human Ig are replaced bycorresponding non-human amino acid residues. Furthermore, humanizedantibodies can contain residues which are not found in the recipientantibody or in the donor antibody. These modifications can be made torefine antibody performance, if needed. A humanized antibody cancomprise substantially all of at least one and, in some cases two,variable domains, in which all or substantially all of the hypervariableregions correspond to those of a non-human immunoglobulin and all, orsubstantially all, of the FRs are those of a human immunoglobulinsequence. The humanized antibody optionally can also include at least aportion of an immunoglobulin constant region (Fc), typically that of ahuman immunoglobulin. For details, see Jones et al., Nature 321: 522-525(1986); Reichmann et al., Nature 332: 323-329 (1988); and Presta, Curr.Op. Struct. Biol. 2: 593-596 (1992).

A humanized antibody also includes antibodies in which part, or all ofthe CDRs of the heavy and light chain are derived from a non-humanmonoclonal antibody, substantially all the remaining portions of thevariable regions are derived from human variable region (both heavy andlight chain), and the constant regions are derived from a human constantregion. In one embodiment, the CDR1, CDR2 and CDR3 regions of the heavyand light chains are derived from a non-human antibody. In yet anotherembodiment, at least one CDR (e.g., a CDR3) of the heavy and lightchains is derived from a non-human antibody. Various combinations ofCDR1, CDR2, and CDR3 can be derived from a non-human antibody and arecontemplated herein. In one non-limiting example, one or more of theCDR1, CDR2 and CDR3 regions of each of the heavy and light chains arederived from a murine chimeric monoclonal antibody clone TRC105.

The term “monoclonal antibody” as used herein refers to an antibodyobtained from a population of substantially homogeneous antibodies,i.e., the individual antibodies comprising the population are identicalexcept for possible naturally occurring mutations that may be present inminor amounts. Monoclonal antibodies are highly specific, being directedagainst a single antigenic site. Furthermore, in contrast toconventional (polyclonal) antibody preparations, which can includedifferent antibodies directed against different determinants (epitopes),each monoclonal antibody is directed against a single determinant on theantigen. The modifier “monoclonal” indicates the character of theantibody as being obtained from a substantially homogeneous populationof antibodies, and is not to be construed as requiring production of theantibody by any particular method. For example, monoclonal antibodiescan be made by the hybridoma method first described by Kohler et al.,Nature 256:495 (1975), or can be made by recombinant DNA methods (see,e.g., U.S. Pat. No. 4,816,567). In certain embodiments, the monoclonalantibodies can be isolated from phage antibody libraries using thetechniques described in Clackson et al., Nature 352:624-628 (1991) andMarks et al., J. Mol. Biol. 222:581-597 (1991), for example.

Antibodies can be isolated and purified from the culture supernatant orascites mentioned above by saturated ammonium sulfate precipitation,euglobulin precipitation method, caproic acid method, caprylic acidmethod, ion exchange chromatography (DEAE or DE52), or affinitychromatography using anti-Ig column or a protein A, G or L column suchas described in more detail below.

Exemplary antibodies for use in the compositions and methods describedherein are intact immunoglobulin molecules, such as, for example, ahumanized antibody or those portions of a humanized Ig molecule thatcontain the antigen binding site (i.e., paratope) or a single heavychain and a single light chain, including those portions known in theart as Fab, Fab′, F(ab)′, F(ab′)₂, Fd, scFv, a variable heavy domain, avariable light domain, a variable NAR domain, bi-specific scFv, abi-specific Fab₂, a tri-specific Fab₃ and a single chain bindingpolypeptides and others also referred to as antigen-binding fragments.When constructing an immunoglobulin molecule or fragments thereof,variable regions or portions thereof may be fused to, connected to, orotherwise joined to one or more constant regions or portions thereof toproduce any of the antibodies or fragments thereof described herein.This may be accomplished in a variety of ways known in the art,including but not limited to, molecular cloning techniques or directsynthesis of the nucleic acids encoding the molecules. Exemplarynon-limiting methods of constructing these molecules can also be foundin the examples described herein.

In one exemplary embodiment, the application contemplates a single chainbinding polypeptide having a heavy chain variable region, and/or a lightchain variable region which binds endoglin and has, optionally, animmunoglobulin Fc region. In one exemplary embodiment, the applicationcontemplates a single chain binding polypeptide having a heavy chainvariable region, and/or a light chain variable region which bindsendoglin and inhibits angiogenesis and has, optionally, animmunoglobulin Fc region. Such a molecule is a single chain variablefragment optionally having effector function or increased half-lifethrough the presence of the immunoglobulin Fc region. Methods ofpreparing single chain binding polypeptides are known in the art (e.g.,U.S. Patent Application No. 2005/0238646).

The terms “germline gene segments” or “germline sequences” refer to thegenes from the germline (the haploid gametes and those diploid cellsfrom which they are formed). The germline DNA contains multiple genesegments that encode a single Ig heavy or light chain. These genesegments are carried in the germ cells but cannot be transcribed andtranslated into heavy and light chains until they are arranged intofunctional genes. During B-cell differentiation in the bone marrow,these gene segments are randomly shuffled by a dynamic genetic systemcapable of generating more than 10⁸ specificities. Most of these genesegments are published and collected by the germline database.

As used herein, “immunoreactive” refers to binding agents, antibodies orfragments thereof that are specific to a sequence of amino acid residues(“binding site” or “epitope”), yet if are cross-reactive to otherpeptides/proteins, are not toxic at the levels at which they areformulated for administration to human use. The term “binding” refers toa direct association between two molecules, due to, for example,covalent, electrostatic, hydrophobic, and ionic and/or hydrogen-bondinteractions under physiological conditions, and including interactionssuch as salt bridges and water bridges and any other conventionalbinding means. The term “preferentially binds” means that the bindingagent binds to the binding site with greater affinity than it bindsunrelated amino acid sequences. Preferably such affinity is at least1-fold greater, at least 2-fold greater, at least 3-fold greater, atleast 4-fold greater, at least 5-fold greater, at least 6-fold greater,at least 7-fold greater, at least 8-fold greater, at least 9-foldgreater, 10-fold greater, at least 20-fold greater, at least 30-foldgreater, at least 40-fold greater, at least 50-fold greater, at least60-fold greater, at least 70-fold greater, at least 80-fold greater, atleast 90-fold greater, at least 100-fold greater, or at least 1000-foldgreater than the affinity of the binding agent for unrelated amino acidsequences. The terms “immunoreactive” and “preferentially binds” areused interchangeably herein.

As used herein, the term “affinity” refers to the equilibrium constantfor the reversible binding of two agents and is expressed as K_(D).Affinity of a binding protein to a ligand such as affinity of anantibody for an epitope can be, for example, from about 100 nanomolar(nM) to about 0.1 nM, from about 100 nM to about 1 picomolar (pM), orfrom about 100 nM to about 1 femtomolar (fM). As used herein, the term“avidity” refers to the resistance of a complex of two or more agents todissociation after dilution. Apparent affinities can be determined bymethods such as an enzyme linked immunosorbent assay (ELISA) or anyother technique familiar to one of skill in the art. Avidities can bedetermined by methods such as a Scatchard analysis or any othertechnique familiar to one of skill in the art.

“Epitope” refers to that portion of an antigen or other macromoleculecapable of forming a binding interaction with the variable regionbinding pocket of an antibody. Such binding interactions can bemanifested as an intermolecular contact with one or more amino acidresidues of one or more CDRs. Antigen binding can involve, for example,a CDR3 or a CDR3 pair or, in some cases, interactions of up to all sixCDRs of the V_(H) and V_(L) chains. An epitope can be a linear peptidesequence (i.e., “continuous”) or can be composed of noncontiguous aminoacid sequences (i.e., “conformational” or “discontinuous”). An antibodycan recognize one or more amino acid sequences; therefore an epitope candefine more than one distinct amino acid sequence. Epitopes recognizedby antibodies can be determined by peptide mapping and sequence analysistechniques well known to one of skill in the art. Binding interactionsare manifested as intermolecular contacts with one or more amino acidresidues of a CDR. TRC105 is a chimeric antibody which is the samevariable amino acid sequence as the murine antibody described as Y4-2F1or SN6j in U.S. Pat. Nos. 5,928,641; 6,200,566; 6,190,660; and7,097,836. Epitopes recognized by Y4-2F1 and SN6j, and thus TRC105, havebeen previously identified.

The term “specific” refers to a situation in which an antibody will notshow any significant binding to molecules other than the antigencontaining the epitope recognized by the antibody. The term is alsoapplicable where for example, an antigen binding domain is specific fora particular epitope which is carried by a number of antigens, in whichcase the antibody or antigen-binding fragment thereof carrying theantigen binding domain will be able to bind to the various antigenscarrying the epitope. The terms “preferentially binds” or “specificallybinds” mean that the antibodies or fragments thereof bind to an epitopewith greater affinity than it binds unrelated amino acid sequences, and,if cross-reactive to other polypeptides containing the epitope, are nottoxic at the levels at which they are formulated for administration tohuman use. In one aspect, such affinity is at least 1-fold greater, atleast 2-fold greater, at least 3-fold greater, at least 4-fold greater,at least 5-fold greater, at least 6-fold greater, at least 7-foldgreater, at least 8-fold greater, at least 9-fold greater, 10-foldgreater, at least 20-fold greater, at least 30-fold greater, at least40-fold greater, at least 50-fold greater, at least 60-fold greater, atleast 70-fold greater, at least 80-fold greater, at least 90-foldgreater, at least 100-fold greater, or at least 1000-fold greater thanthe affinity of the antibody or fragment thereof for unrelated aminoacid sequences. The terms “immunoreactive,” “binds,” “preferentiallybinds” and “specifically binds” are used interchangeably herein. Theterm “binding” refers to a direct association between two molecules, dueto, for example, covalent, electrostatic, hydrophobic, and ionic and/orhydrogen-bond interactions under physiological conditions, and includesinteractions such as salt bridges and water bridges, as well as anyother conventional means of binding.

The phrase “conservative amino acid substitution” refers to grouping ofamino acids on the basis of certain common properties. A functional wayto define common properties between individual amino acids is to analyzethe normalized frequencies of amino acid changes between correspondingproteins of homologous organisms (Schulz, G. E. and R. H. Schirmer,Principles of Protein Structure, Springer-Verlag). According to suchanalyses, groups of amino acids may be defined where amino acids withina group exchange preferentially with each other, and therefore resembleeach other most in their impact on the overall protein structure(Schulz, G. E. and R. H. Schirmer, Principles of Protein Structure,Springer-Verlag). Examples of amino acid groups defined in this mannerinclude:

-   -   (i) a charged group, consisting of Glu and Asp, Lys, Arg and        His,    -   (ii) a positively-charged group, consisting of Lys, Arg and His,    -   (iii) a negatively-charged group, consisting of Glu and Asp,    -   (iv) an aromatic group, consisting of Phe, Tyr and Trp,    -   (v) a nitrogen ring group, consisting of His and Trp,    -   (vi) a large aliphatic non-polar group, consisting of Val, Leu        and Ile,    -   (vii) a slightly-polar group, consisting of Met and Cys,    -   (viii) a small-residue group, consisting of Ser, Thr, Asp, Asn,        Gly, Ala, Glu, Gln and Pro,    -   (ix) an aliphatic group consisting of Val, Leu, Ile, Met and        Cys, and    -   (x) a small hydroxyl group consisting of Ser and Thr.

In addition to the groups presented above, each amino acid residue mayform its own group, and the group formed by an individual amino acid maybe referred to simply by the one and/or three letter abbreviation forthat amino acid commonly used in the art as described above.

A “conserved residue” is an amino acid that is relatively invariantacross a range of similar proteins. Often conserved residues will varyonly by being replaced with a similar amino acid, as described above for“conservative amino acid substitution.”

The letter “x” or “xaa” as used in amino acid sequences herein isintended to indicate that any of the twenty standard amino acids may beplaced at this position unless specifically noted otherwise. For thepurposes of peptidomimetic design, an “x” or a “xaa” in an amino acidsequence may be replaced by a mimic of the amino acid present in thetarget sequence, or the amino acid may be replaced by a spacer ofessentially any form that does not interfere with the activity of thepeptidomimetic.

“Homology” or “identity” or “similarity” refers to sequence similaritybetween two peptides or between two nucleic acid molecules. Homology andidentity can each be determined by comparing a position in each sequencewhich may be aligned for purposes of comparison. When an equivalentposition in the compared sequences is occupied by the same base or aminoacid, then the molecules are identical at that position; when theequivalent site occupied by the same or a similar amino acid residue(e.g., similar in steric and/or electronic nature), then the moleculescan be referred to as homologous (similar) at that position. Expressionas a percentage of homology/similarity or identity refers to a functionof the number of identical or similar amino acids at positions shared bythe compared sequences. A sequence which is “unrelated” or“non-homologous” shares less than 40% identity, though preferably lessthan 25% identity with a sequence of the present invention. In comparingtwo sequences, the absence of residues (amino acids or nucleic acids) orpresence of extra residues also decreases the identity andhomology/similarity.

The term “homology” describes a mathematically based comparison ofsequence similarities which is used to identify genes or proteins withsimilar functions or motifs. The nucleic acid (nucleotide,oligonucleotide) and amino acid (protein) sequences of the presentinvention may be used as a “query sequence” to perform a search againstpublic databases to, for example, identify other family members, relatedsequences or homologs. Such searches can be performed using the NBLASTand XBLAST programs (version 2.0) of Altschul, et al. (1990) J. Mol.Biol. 215:403-10. BLAST nucleotide searches can be performed with theNBLAST program, score=100, wordlength=12 to obtain nucleotide sequenceshomologous to nucleic acid molecules of the invention. BLAST amino acidsearches can be performed with the XBLAST program, score=50,wordlength=3 to obtain amino acid sequences homologous to proteinmolecules of the invention. To obtain gapped alignments for comparisonpurposes, Gapped BLAST can be utilized as described in Altschul et al.,(1997) Nucleic Acids Res. 25(17):3389-3402. When utilizing BLAST andGapped BLAST programs, the default parameters of the respective programs(e.g., XBLAST and BLAST) can be used (see, www.ncbi.nlm.nih.gov).

As used herein, “identity” means the percentage of identical nucleotideor amino acid residues at corresponding positions in two or moresequences when the sequences are aligned to maximize sequence matching,i.e., taking into account gaps and insertions. Identity can be readilycalculated by known methods, including but not limited to thosedescribed in (Computational Molecular Biology, Lesk, A. M., ed., OxfordUniversity Press, New York, 1988; Biocomputing: Informatics and GenomeProjects, Smith, D. W., ed., Academic Press, New York, 1993; ComputerAnalysis of Sequence Data, Part I, Griffin, A. M., and Griffin, H. G.,eds., Humana Press, New Jersey, 1994; Sequence Analysis in MolecularBiology, von Heinje, G., Academic Press, 1987; and Sequence AnalysisPrimer, Gribskov, M. and Devereux, J., eds., M Stockton Press, New York,1991; and Carillo, H., and Lipman, D., SIAM J. Applied Math., 48: 1073(1988). Methods to determine identity are designed to give the largestmatch between the sequences tested. Moreover, methods to determineidentity are codified in publicly available computer programs. Computerprogram methods to determine identity between two sequences include, butare not limited to, the GCG program package (Devereux, J., et al.,Nucleic Acids Research 12(1): 387 (1984)), BLASTP, BLASTN, and FASTA(Altschul, S. F. et al., J. Molec. Biol. 215: 403-410 (1990) andAltschul et al. Nuc. Acids Res. 25: 3389-3402 (1997)). The BLAST Xprogram is publicly available from NCBI and other sources (BLAST Manual,Altschul, S., et al., NCBI NLM NIH Bethesda, Md. 20894; Altschul, S., etal., J. Mol. Biol. 215: 403-410 (1990). The well known Smith Watermanalgorithm may also be used to determine identity.

“Isolated” (used interchangeably with “substantially pure”) when appliedto polypeptides means a polypeptide or a portion thereof which, byvirtue of its origin or manipulation: (i) is present in a host cell asthe expression product of a portion of an expression vector; or (ii) islinked to a protein or other chemical moiety other than that to which itis linked in nature; or (iii) does not occur in nature, for example, aprotein that is chemically manipulated by appending, or adding at leastone hydrophobic moiety to the protein so that the protein is in a formnot found in nature. By “isolated” it is further meant a protein thatis: (i) synthesized chemically; or (ii) expressed in a host cell andpurified away from associated and contaminating proteins. The termgenerally means a polypeptide that has been separated from otherproteins and nucleic acids with which it naturally occurs. Preferably,the polypeptide is also separated from substances such as antibodies orgel matrices (polyacrylamide) which are used to purify it.

As used herein, the terms “angiogenesis inhibitory,” “angiogenesisinhibiting” or “anti-angiogenic” include vasculogenesis, and areintended to mean effecting a decrease in the extent, amount, or rate ofneovascularization. Effecting a decrease in the extent, amount, or rateof endothelial cell proliferation or migration in the tissue is aspecific example of inhibiting angiogenesis.

The term “angiogenesis inhibitory composition” refers to a compositionwhich inhibits angiogenesis-mediated processes such as endothelial cellmigration, proliferation, tube formation and subsequently leading to theinhibition of the generation of new blood vessels from existing ones,and consequently affects angiogenesis-dependent conditions.

As used herein, the term “angiogenesis-dependent condition” is intendedto mean a condition where the process of angiogenesis or vasculogenesissustains or augments a pathological condition or beneficially influencesnormal physiological processes. Therefore, treatment of anangiogenesis-dependent condition in which angiogenesis sustains apathological condition could result in mitigation of disease, whiletreatment of an angiogenesis-dependent condition in which angiogenesisbeneficially influences normal physiological processes could result in,e.g., enhancement of a normal process.

Angiogenesis is the formation of new blood vessels from pre-existingcapillaries or post-capillary venules. Vasculogenesis results from theformation of new blood vessels arising from angioblasts which areendothelial cell precursors. Both processes result in new blood vesselformation and are included in the meaning of the termangiogenesis-dependent conditions. The term “angiogenesis” as usedherein is intended to include de novo formation of vessels such as thatarising from vasculogenesis as well as those arising from branching andsprouting of existing vessels, capillaries and venules. Angiogenesis canalso be inclusive of induction of ALK1 signaling and related Smad 1/5/8phosphorylation and/or signaling. CD105 is also known to be involved inthe ALK1 signaling pathway and is thus also included within the meaningof angiogenesis.

“Inducing a host immune response” means that a patient experiencesalleviation or reduction of signs or symptoms of illness, andspecifically includes, without limitation, prolongation of survival. Incertain preferred embodiments of the methods according to the invention,a CD8+ IFN-γ producing T cell is activated to induce a cytotoxic Tlymphocyte (CTL) immune response in the patient administered theantagonist. In certain embodiments of the methods according to theinvention, a CD4+IFN-γ producing T cell is activated to induce a helperT cell immune response in the patient administered with the composition.These activated CD4+IFN-γ producing T cells (i.e., helper T cells)provide necessary immunological help (e.g., by release of cytokines) toinduce and maintain not only CTL, but also a humoral immune responsemediated by B cells. Thus, in certain embodiments of the methodsaccording to the invention, a humoral response to the antigen isactivated in the patient administered with the composition. In oneaspect, an adjuvant may be added to the composition to increase animmune response. Adjuvants are well-known in the art.

Activation of a CD8+ and/or CD4+ T cells means causing T cells that havethe ability to produce cytokines (e.g., IFN-γ) to actually produce oneor more cytokine(s), or to increase their production of one or morecytokine(s). “Induction of CTL response” means causing potentiallycytotoxic T lymphocytes to exhibit antigen specific cytotoxicity.“Antigen specific cytotoxicity” means cytotoxicity against a cellpresenting an antigen that is associated with the antigen associatedwith, the cancer that is greater than an antigen that is not associatedwith a cancer. “Cytotoxicity” refers to the ability of the cytotoxic Tlymphocyte to kill a target cell. Such antigen-specific cytotoxicity canbe at least about 3-fold, at least about 10-fold greater, at least about100-fold greater or more than cytotoxicity against a cell not presentingthe antigen not associated with the cancer. Antibody dependentcell-mediated cytotoxicity (ADCC) also includes activation of naturalkiller cells (“NK cells”) which mediate cell killing via antibodybinding. The antibodies and antigen-binding fragments described hereincan mediate ADCC via NK cells through the binding of endoglin.

As used herein, the terms “proliferative disorder” and “proliferativecondition” mean any pathological or non-pathological physiologicalcondition characterized by aberrant or undesirable proliferation. Theterms “cell proliferative disorder” and “cell proliferative condition”mean any pathological or non-pathological physiological conditioncharacterized by aberrant or undesirable cell proliferation, as well asincluding conditions characterized by undesirable or unwanted cellproliferation or cell survival (e.g., due to deficient apoptosis),conditions characterized by deficient or aberrant or deficientapoptosis, as well as conditions characterized by aberrant orundesirable or unwanted cell survival. The term “differentiativedisorder” means any pathological or non-pathological physiologicalcondition characterized by aberrant or deficient differentiation.

Proliferative or differentiative disorders amenable to treatment includediseases and non-pathological physiological conditions, benign andneoplastic, characterized by abnormal or undesirable cell numbers, cellgrowth or cell survival. Such disorders or conditions may thereforeconstitute a disease state and include all types of cancerous growths oroncogenic processes, metastatic tissues or malignantly transformedcells, tissues, or organs, or may be non-pathologic, i.e., a deviationfrom normal but which is not typically associated with disease. Aspecific example of a non-pathologic condition that may be treated inaccordance with the invention is tissue re-growth from wound repair thatresults in scarring.

Cells comprising the proliferative or differentiative disorder may beaggregated in a cell mass or be dispersed. The term “solid tumor” refersto neoplasias or metastases that typically aggregate together and form amass. Particular examples include visceral tumors such as gastric orcolon cancer, hepatomas, venal carcinomas, lung and braintumors/cancers. A “non-solid tumor” refers to neoplasias of thehematopoietic system, such as lymphomas, myelomas and leukemias, orneoplasias that are diffuse in nature, as they do not typically form asolid mass. Particular examples of leukemias include for example, acuteand chronic lymphoblastic, myeloblastic and multiple myeloma.

Such disorders include neoplasms or cancers, which can affect virtuallyany cell or tissue type, e.g., carcinoma, sarcoma, melanoma, metastaticdisorders or hematopoietic neoplastic disorders. A metastatic tumor canarise from a multitude of primary tumor types, including but not limitedto breast, lung, thyroid, head and neck, brain, lymphoid,gastrointestinal (mouth, esophagus, stomach, small intestine, colon,rectum), genito-urinary tract (uterus, ovary, cervix, bladder, testicle,penis, prostate), kidney, pancreas, liver, bone, muscle, skin, etc.

Carcinomas refer to malignancies of epithelial or endocrine tissue, andinclude respiratory system carcinomas, gastrointestinal systemcarcinomas, genitourinary system carcinomas, testicular carcinomas,breast carcinomas, prostatic carcinomas, endocrine system carcinomas,and melanomas. Exemplary carcinomas include those forming from thecervix, lung, prostate, breast, head and neck, colon, liver and ovary.The term also includes carcinosarcomas, e.g., which include malignanttumors composed of carcinomatous and sarcomatous tissues. Adenocarcinomaincludes a carcinoma of a glandular tissue, or in which the tumor formsa gland like structure.

An ocular tissue to be treated is, for example, a retinal tissue of apatient with diabetic retinopathy, macular degeneration or neovascularglaucoma and the angiogenesis to be inhibited is retinal tissueangiogenesis where there is neovascularization of retinal tissue.

A cancerous tissue to be treated is, for example, an endothelial tissueexpressing an abnormal level of endoglin. As used herein, the term“transformed cells” refers to cells that have spontaneously converted toa state of unrestrained growth, i.e., they have acquired the ability togrow through an indefinite number of divisions in culture. Transformedcells may be characterized by such terms as neoplastic, anaplasticand/or hyperplastic, with respect to their loss of growth control. Forpurposes of this invention, the terms “transformed phenotype ofmalignant mammalian cells” and “transformed phenotype” are intended toencompass, but not be limited to, any of the following phenotypic traitsassociated with cellular transformation of mammalian cells:immortalization, morphological or growth transformation, andtumorigenicity, as detected by prolonged growth in cell culture, growthin semi-solid media, or tumorigenic growth in immuno-incompetent orsyngeneic animals.

The term “tumor cell antigen” is defined herein as an antigen that ispresent in higher quantities on a tumor cell or in body fluids thanunrelated tumor cells, normal cells, or in normal body fluid. Theantigen presence may be tested by any number of assays known to thoseskilled in the art and include without limitation negative and/orpositive selection with antibodies, such as an ELISA assay, aradioimmunoassay, or by Western Blot.

The terms “apoptosis” or “programmed cell death,” refers to thephysiological process by which unwanted or useless cells are eliminatedduring development and other normal biological processes. Apoptosis is amode of cell death that occurs under normal physiological conditions andthe cell is an active participant in its own demise (“cellularsuicide”). It is most often found during normal cell turnover and tissuehomeostasis, embryogenesis, induction and maintenance of immunetolerance, development of the nervous system and endocrine-dependenttissue atrophy. Cells undergoing apoptosis show characteristicmorphological and biochemical features. These features include chromatinaggregation, nuclear and cytoplasmic condensation, partition ofcytoplasm and nucleus into membrane bound vesicles (apoptotic bodies),which contain ribosomes, morphologically intact mitochondria and nuclearmaterial. In vivo, these apoptotic bodies are rapidly recognized andphagocytized by macrophages, dendritic cells or adjacent epithelialcells. Due to this efficient mechanism for the removal of apoptoticcells in vivo no inflammatory response is elicited. In vitro, theapoptotic bodies as well as the remaining cell fragments ultimatelyswell and finally lyse. This terminal phase of in vitro cell death hasbeen termed “secondary necrosis.” Apoptosis can be measured by methodsknown to those skilled in the art like DNA fragmentation, exposure ofAnnexin V, activation of caspases, release of cytochrome c, etc. A cellthat has been induced to die is termed herein as an “apoptotic cell.”

“Apoptosis inducing agent” is defined herein to induceapoptosis/programmed cell death, and include, for example, irradiation,chemotherapeutic agents or receptor ligation agents, wherein cells, forexample, tumor cells are induced to undergo programmed cell death.Exemplary apoptosis inducing agents are described in more detail below.

Apoptosis can be tested using a standard Annexin V Apoptosis Assay:NIH:OVCAR-3 cells are grown in 6-well plates (NUNC) and irradiated ortreated with an antagonist (or in combination with another anti-cancerdrug) for 4-48 hours, washed and stained with Annexin V-FITC(BD-Pharmingen) for 1 hour. Cells are analyzed by flow cytometry(Becton-Dickinson, CellQuest), counterstained with Propidium Iodide andanalyzed again in the flow cytometer.

B. Methods of Making and Expressing Humanized Anti-Endoglin Antibodies

A chimeric monoclonal antibody has been developed that binds endoglin.This antibody is designated TR105 (also known as c-SN6j).

In one aspect, the antibodies and antigen-binding fragments thereofdescribed herein were created by humanization of the V_(L) and V_(H)sequences of the chimeric monoclonal TRC105 antibody (SEQ ID NOS. 1 and39, respectively).

Humanized immunoglobulins, including humanized antibodies, have beenconstructed by means of genetic engineering. Most humanizedimmunoglobulins that have been previously described have comprised aframework that is identical to the framework of a particular humanimmunoglobulin chain (i.e., an acceptor or recipient), and three CDRsfrom a non-human (i.e., donor) immunoglobulin chain. As describedherein, humanization can also include criteria by which a limited numberof amino acids in the framework of a humanized immunoglobulin chain areidentified and chosen to be the same as the amino acids at thosepositions in the donor rather than in the acceptor, in order to increaseor maintain the affinity of an antibody comprising the humanizedimmunoglobulin chain.

The present invention is based in part on the model that twocontributing causes of the loss of affinity in prior means of producinghumanized antibodies (using as examples mouse antibodies as the sourceof CDRs) are: (1) when the mouse CDRs are combined with a humanframework, the amino acids in the frameworks close to the CDRs becomehuman instead of mouse. Without intending to be bound by theory, thesechanged amino acids may slightly distort the CDRs (e.g., they may createdifferent electrostatic or hydrophobic forces than in the donor mouseantibody, and the distorted-CDRs may not make as effective contacts withthe antigen as the CDRs did in the donor antibody); (2) also, aminoacids in the original mouse antibody that are close to, but not part of,the CDRs (i.e., still part of the framework), may make contacts with theantigen that contribute to affinity. These amino acids are lost when theantibody is humanized because, generally, all framework amino acids aremade human. To circumvent these issues, and to produce humanizedantibodies that have a very strong affinity for a desired antigen,humanized antibodies and antigen-binging fragments thereof can beconstructed using one or more of the following principles.

One non-limiting principle is that, for example, as acceptor, aframework is used from a particular human immunoglobulin that isunusually homologous to the donor immunoglobulin to be humanized, or usea consensus framework from many human antibodies is used as an acceptor.For example, comparison of the sequence of a mouse heavy (or light)chain variable region against human heavy (or light) variable regions ina data bank (for example, the National Biomedical Research FoundationProtein Identification Resource or the protein sequence database of theNational Center for Biotechnology Information—NCBI) shows that theextent of homology to different human regions can vary greatly, forexample from about 40% to about 60%, about 70%, about 80% or higher. Bychoosing as the acceptor immunoglobulin one of the human heavy chainvariable regions that is most homologous to the heavy chain variableregion of the donor immunoglobulin, fewer amino acids will be changed ingoing from the donor immunoglobulin to the humanized immunoglobulin. Bychoosing as the acceptor immunoglobulin one of the human light chainvariable regions that is most homologous to the light chain variableregion of the donor immunoglobulin, fewer amino acids will be changed ingoing from the donor immunoglobulin to the humanized immunoglobulin.Generally, using such techniques, there is a reduced chance of changingan amino acid near one or more of the CDRs that distorts theirconformation. Moreover, the precise overall shape of a humanizedantibody comprising the humanized immunoglobulin chain may more closelyresemble the shape of the donor antibody, thereby also reducing thechance of distorting the CDRs.

One can also use light and heavy chains from the same human antibody asacceptor sequences, to improve the likelihood that the humanized lightand heavy chains will make favorable contacts with each other.Alternatively, one can also use light and heavy chains from differenthuman antibody germline sequences as acceptor sequences; when suchcombinations are used, one can readily determine whether the V_(H) andV₁ bind an epitope of interest using conventional assays (e.g., anELISA). In one example, the human antibody will be chosen in which thelight and heavy chain variable regions sequences, taken together, areoverall most homologous to the donor light and heavy chain variableregion sequences. Sometimes greater weight will be given to the heavychain sequence. Regardless of how the acceptor immunoglobulin is chosen,higher affinity can, in some cases, be achieved by selecting a smallnumber of amino acids in the framework of the humanized immunoglobulinchain to be the same as the amino acids at those positions in the donorrather than in the acceptor. Methods of affinity maturation are known inthe art.

Humanized antibodies generally have at least three potential advantagesover mouse or chimeric antibodies for use in human therapy. Because theeffector portion of an antibody is human, it is believed to interactbetter with the other parts of the human immune system (e.g., destroythe target cells more efficiently by complement-dependent cytotoxicity(CDC) or antibody-dependent cellular cytotoxicity (ADCC)). Additionally,the human immune system should not recognize the framework or constantregion of the humanized antibody as foreign, and therefore the antibodyresponse against such an injected antibody should be less than against atotally foreign mouse antibody or a partially foreign chimeric antibody.Finally, mouse antibodies are known to have a half-life in the humancirculation that is much shorter than the half-life of human antibodies.Humanized antibodies can, presumably, have a half-life more similar tonaturally-occurring human antibodies, allowing smaller and less frequentdoses to be given.

Humanization of antibodies and antigen-binding fragments thereof, can beaccomplished via a variety of methods known in the art and describedherein. Similarly, production of humanized antibodies can also beaccomplished via methods known in the art and described herein.

Methods for modifications of framework regions are known in the art andare contemplated herein. Selection of one or more relevant frameworkamino acid positions to altered depends on a variety of criteria. Onecriterion for selecting relevant framework amino acids to change can bethe relative differences in amino acid framework residues between thedonor and acceptor molecules. Selection of relevant framework positionsto alter using this approach has the advantage of avoiding anysubjective bias in residue determination or any bias in CDR bindingaffinity contribution by the residue.

Another criterion that can be used for determining the relevant aminoacid positions to change can be, for example, selection of frameworkresidues that are known to be important or to contribute to CDRconformation. For example, canonical framework residues are importantfor CDR conformation and/or structure. Targeting of a canonicalframework residue as a relevant position to change can be used toidentify a more compatible amino acid residue in context with itsassociated donor CDR sequence.

The frequency of an amino acid residue at a particular frameworkposition is another criterion which can be used for selecting relevantframework amino acid positions to change. For example, comparison of theselected framework with other framework sequences within its subfamilycan reveal residues that occur at minor frequencies at a particularposition or positions. Positions harboring less abundant residues aresimilarly applicable for selection as a position to alter in theacceptor variable region framework.

The relevant amino acid positions to change also can be selected, forexample, based on proximity to a CDR. In certain contexts, FR residuescan participate in CDR conformation and/or antigen binding. Moreover,this criterion can similarly be used to prioritize relevant positionsselected by other criteria described herein. Therefore, differentiatingbetween residues proximal and distal to one or more CDRs represents oneway to reduce the number of relevant positions to change.

Other criteria for selecting relevant amino acid framework positions toalter include, for example, residues that are known or predicted toreside in a three dimensional space near the antigen-CDR interface orpredicted to modulate CDR activity. Similarly, framework residues thatare known to, or predicted to, form contacts between the heavy (V_(H))and light (V_(L)) chain variable region interface can be selected. Suchframework positions can affect the conformation and/or affinity of a CDRby modulating the CDR binding pocket, antigen (epitope) interaction orthe V_(H) and V_(L) interaction. Therefore, selection of these aminoacid positions for constructing a diverse population for screening ofbinding activity can be used to identify framework changes which replaceresidues having detrimental effects on CDR conformation or compensatefor detrimental effects of residues occurring elsewhere in theframework.

Other framework residues that can be selected for alteration includeamino acid positions that are inaccessible to solvent. Such residues aregenerally buried in the variable region and are, therefore, capable ofinfluencing the conformation of the CDR or V_(H) and V_(L) interactions.Solvent accessibility can be predicted, for example, from the relativehydrophobicity of the environment created by the amino acid side chainsof the polypeptide and/or by known three-dimensional structural data.

Following selection of relevant amino acid positions in the donor CDRs,as well as any relevant amino acid positions in the framework regionsdesired to be varied, amino acid changes at some or all of the selectedpositions can be incorporated into encoding nucleic acids for theacceptor variable region framework and donor CDRs. Altered framework orCDR sequences can be individually made and tested, or can besequentially or simultaneously combined and tested.

The variability at any or all of the altered positions can range from afew to a plurality of different amino acid residues, including alltwenty naturally occurring amino acids or functional equivalents andanalogues thereof. In some cases, non-naturally occurring amino acidsmay also be considered and are known in the art.

Selection of the number and location of the amino acid positions to varyis flexible and can depend on the intended use and desired efficiencyfor identification of the altered variable region having a desirableactivity such as substantially the same or greater binding affinitycompared to the donor variable region. In this regard, the greater thenumber of changes that are incorporated into an altered variable regionpopulation, the more efficient it is to identify at least one speciesthat exhibits a desirable activity, for example, substantially the sameor greater binding affinity as the donor. Alternatively, where the userhas empirical or actual data to the affect that certain amino acidresidues or positions contribute disproportionally to binding affinity,then it can be desirable to produce a limited population of alteredvariable regions which focuses on changes within or around thoseidentified residues or positions.

For example, if CDR grafted variable regions are desired, a large,diverse population of altered variable regions can include all thenon-identical framework region positions between the donor and acceptorframework and all single CDR amino acid position changes. Alternatively,a population of intermediate diversity can include subsets, for example,of only the proximal non-identical framework positions to beincorporated together with all single CDR amino acid position changesto, for example, increase affinity of the humanized antibodies orantigen binding fragments. The diversity of the above populations can befurther increased by, for example, additionally including all pair-wiseCDR amino acid position changes. In contrast, populations focusing onpredetermined residues or positions which incorporate variant residuesat as few as one framework and/or one CDR amino acid position cansimilarly be constructed for screening and identification of an alteredantibody variable region. As with the above populations, the diversityof such focused populations can be further increased by additionallyexpanding the positions selected for change to include other relevantpositions in either or both of the framework and CDR regions. There arenumerous other combinations ranging from few changes to many changes ineither or both of the framework regions and CDRs that can additionallybe employed, all of which will result in a population of alteredvariable regions that can be screened for the identification of at leastone CDR grafted altered variable region having desired activity, forexample, binding activity to endoglin. Those skilled in the art willknow, or can determine, which selected residue positions in theframework or donor CDRs, or subsets thereof, can be varied to produce apopulation for screening and identification of an altered antibody ofthe invention given the teachings and guidance provided herein. Codonsencoding amino acids are known in the art.

Another method of humanizing antibodies includes a method termed“superhumanization.” Superhumanization involves the steps of obtaining apeptide sequence for a subject variable region encoded by a non-humanmature antibody gene and identifying a first set of canonical CDRstructure types for at least two CDRs within the non-human antibodyvariable region. Canonical CDR structure types are the structure typesdesignated by Chothia (CITE). Chothia and coworkers found that criticalportions of the CDRs of many antibodies adopt nearly identical peptidebackbone conformations, despite great diversity at the level of aminoacid sequence. Accordingly, Chothia defined for each CDR in each chainone or a few “canonical structures.” Each canonical structure specifiesprimarily a set of peptide backbone torsion angles for a contiguoussegment of amino acid residues forming a loop.

After the identification of the canonical CDR structure type, a libraryof peptide sequences for human antibody variable regions for humanantibodies is also obtained. This library contains sequences for humangermline variable regions as encoded by germline nucleic acid segments,and may include mature human antibody sequences. In either case, themethod includes identifying canonical CDR structure types (i.e., asecond set of canonical CDR structure types) for at least two CDRs foreach sequence within the library of human variable region sequences.From this library there is selected a subset of candidate sequences bycomparing the first set of canonical CDR structure types to the secondset of canonical CDR structure types (i.e., comparing the mousecanonical CDR structure types to the human canonical CDR structure typesat corresponding locations within the variable region) and selectingthose human sequences where the second set of canonical CDR structure isthe same as the first set of canonical CDR structure types for the CDRsequences at corresponding locations within the non-human and humanvariable regions, respectively. The method uses these candidate humanvariable region sequences as a basis for constructing a chimericmolecule that includes at least two of the CDR sequences from thenon-human variable region (e.g., of the mouse CDRs) combined with theframework regions from candidate human variable region sequences. Theresult of the construction is that the chimeric antibody contains eachof the non-human CDR sequences substituted for each of the human CDRsequences at corresponding locations in the variable regions so that theframework sequences in the chimeric antibody differs from the candidatehuman framework sequences.

The similarity to the subject CDRs of candidate human antibody sequencesis assessed for each domain at two levels. Primarily, identicalthree-dimensional conformations of CDR peptide backbones are sought.Experimentally determined atomic coordinates of the subject CDRs areseldom available, hence three-dimensional similarity is approximated bydetermining Chothia canonical structure types of the subject CDRs andexcluding from further consideration candidates possessing differentcanonical structures. Secondarily, residue-to-residue homology betweensubject CDRs and the remaining human candidate CDRs is considered, andthe candidate with the highest homology is chosen.

Choosing highest homology is based on various criterion used to rankcandidate human variable regions having the same canonical structure asthe subject the non-human variable regions. The criterion for rankingmembers of the selected set may be by amino acid sequence identity oramino acid homology or both. Amino acid identity is simple a score ofposition by position matches of amino acid residues. Similarity by aminoacid homology is position by position similarity in residue structure ofcharacter. Homology may be scored, for example, according to the tablesand procedures described by Henikoff and Henikoff, (1992) Amino acidsubstitution matrices from protein blocks, Proc. Natl. Acad. Sci. 89:10915-10919, or by the BLOSUM series described by Henikoff and Henikoff,(1996). The steps are as follows:

-   -   a) Determine the peptide sequences of the heavy and light chain        variable domains of the subject antibody. These can be        determined by any of several methods, such as DNA sequencing of        the respective genes after conventional cDNA cloning; DNA        sequencing of cloning products that have been amplified by the        polymerase chain reaction from reverse transcripts or DNA of the        subject hybridoma line; or peptide sequencing of a purified        antibody protein.    -   b) Apply the Kabat numbering system (Kabat et al, Id. 1991) to        the heavy and light chain sequences of the subject non-human        antibody. Determine canonical structure types for each of the        CDRs of the subject non-human antibody. This determination is        made from examination of the peptide sequence in light of the        guidelines discussed in Chothia and Lesk (1987), Chothia et al        (1992), Tomlinson et al (1995), Martin and Thornton (1996), and        Al-Lazikani et al (1997).

The salient features of canonical structure determination for each ofthe CDRs are as follows. For heavy chain CDR1, three canonical structuretypes are currently known. Assignment of a new sequence isstraightforward because each canonical structure type has a differentnumber of residues. As described in Al-Lazikani et. al (1997), whenKabat numbering is assigned to the sequence, the numbering for residues31-35 will be as follows for the respective canonical structures.

Canonical structure type 1: 31, 32, 33, 34, 35.

Canonical structure type 2: 31, 32, 33, 34, 35, 35a.

Canonical structure type 3: 31, 32, 33, 34, 35, 35a, 35b.

For heavy chain CDR2, four canonical structure types are currentlyknown. Several have unique numbers of residues, and are easilydistinguished from their unique Kabat numbering of positions 52-56,viz.:

Canonical structure type 1: 52, 53, 54, 55, 56.

Canonical structure type 4: 52, 52a, 52b, 52c, 53, 54, 55, 56.

Canonical structure types 2 and 3 for heavy chain CDR2 have equalnumbers of residues, hence must be distinguished by clues within theirsequence, as discussed by Chothia et al (1992). The Kabat numbering ofthe segment containing these clues is: 52, 52a, 53, 54, 55. Canonicalstructure type 2 has Pro or Ser at position 52a and Gly or Ser atposition 55, with no restriction at the other positions. Canonicalstructure type 3 has Gly, Ser, Asn, or Asp at position 54, with norestriction at the other positions. These criteria are sufficient toresolve the correct assignment in most cases. Additionally, frameworkresidue 71 is commonly Ala, Val, Leu, Ile, or Thr for canonicalstructure type 2 and commonly Arg for canonical structure type 3.

Heavy chain CDR3 is the most diverse of all the CDRs. It is generated bygenetic processes, some of a random nature, unique to lymphocytes.Consequently, canonical structures for CDR3 have been difficult topredict. In any case, human germ line V gene segments do not encode anypart of CDR3; because the V gene segments end at Kabat position 94,whereas positions 95 to 102 encode CDR3. For these reasons, canonicalstructures of CDR3 are generally not considered for choosing candidatehuman sequences.

For light chain CDR1, six canonical structure types are currently knownfor CDR1 in kappa chains. Each canonical structure type has a differentnumber of residues, hence assignment of a canonical structure type to anew sequence is apparent from the Kabat numbering of residue positions27-31.

Canonical structure type I: 27, 29, 30, 31.

Canonical structure type 2: 27, 28, 29, 30, 31.

Canonical structure type 3: 27, 27a, 27b, 27c, 27d, 27e, 27f, 28, 29,30, 31.

Canonical structure type 4: 27, 27a, 27b, 27c, 27d, 27e, 28, 29, 30, 31.

Canonical structure type 5: 27, 27a, 27b, 27c, 27d, 28, 29, 30, 31.

Canonical structure type 6: 27, 27a, 28, 29, 30, 31.

For light chain CDR2, only a single canonical structure type is knownfor CDR2 in kappa chains, hence, barring exceptional subject antibodysequences, assignment is automatic. For light chain CDR3, up to sixcanonical structure types have been described for CDR3 in kappa chains,but three of these are rare. The three common ones can be distinguishedby their length, reflected in Kabat numbering of residue positions91-97:

Canonical structure type 1: 91, 92, 93, 94, 95, 96, 97 (also with anobligatory Pro at position 95 and Gln, Asn, or His at position 90).

Canonical structure type 3: 91, 92, 93, 94, 95, 97.

Canonical structure type 5: 91, 92, 93, 94, 95, 96, 96a, 97.

After identifying the canonical CDR structure types of the subjectnon-human antibody, human genes of the same chain type (heavy or light)that have the same combination of canonical structure types as thesubject antibody are identified to form a candidate set of humansequences. Most of these gene fragments have been discovered and havealready been assigned to a canonical structure type (Chothia et al,1992, Tomlinson et al, 1995).

For the heavy chain, conformity of CDR1 and CDR2 to the mouse canonicalstructure types is assessed, and genes that do not conform are excluded.For the light chain, conformity of CDR1 and CDR2 of each human sequenceto the canonical structure types of the subject antibody is firstassessed. The potential of residues 89-95 of a candidate Vk gene to forma CDR3 of the same canonical structure type as the subject antibody isassessed, by positing a fusion of the gene with a J region and applyingcriteria for CDR3 canonical CDR structure type determination to thefused sequence, and non conforming sequences are excluded.

Alternatively, when a variable domain of the subject antibody is of acanonical structure type not available in the human genome, humangermline V genes that have three-dimensionally similar, but notidentical, canonical structure types are considered for comparison. Sucha circumstance often occurs with kappa chain CDR1 in murine antibodies,including two of the examples described below. All 6 possible canonicalstructure types have been observed at this CDR in murine antibodies,whereas the human genome encodes only canonical types 2, 3, 4 and 6. Inthese circumstances, a canonical CDR structure type having length ofamino acid residues within two of the length of the amino acid residuesof the subject non-human sequence may selected for the comparison. Forexample, where a type 1 canonical structure is found in the subjectantibody, human Vk sequences with canonical structure type 2 are usedfor comparison. Where a type 5 canonical structure is found in themurine antibody, human Vk sequences with either canonical structure type3 or 4 are be used for comparison.

Mature, rearranged human antibody sequences can be considered for thesequence comparison. Such consideration might be warranted under avariety of circumstances, including but not limited to instances wherethe mature human sequence (1) is very close to germline; (2) is knownnot to be immunogenic in humans; or (3) contains a canonical structuretype identical to that of the subject antibody, but not found in thehuman germ line.

For each of the candidate V genes with matching canonical structuretypes, residue to residue sequence identity and/or homology with thesubject sequence is also evaluated to rank the candidate humansequences. For example, the residues evaluated are as follows: (1) Kappa(K) light chain CDR amino acid residue positions are CDR1 (26-32), CDR2(50-52), CDR3 (91-96); and (2) heavy chain CDR amino acid residuepositions are CDR1 (31-35) and CDR2 (50-60). Additionally, heavy chainCDR3 amino acid residue positions 95 to 102 can also be considered.

Residue-to-residue homology is first scored by the number of identicalamino acid residues between the subject and the candidate humansequences. The human sequence used for subsequent construction of aconverted antibody is chosen from among the 25 percent of candidateswith the highest score. When appropriate, such as when several candidatesequences have similar identity scores, similarity between non-identicalamino acid residues may be additionally considered as needed.Aliphatic-with-aliphatic, aromatic-with-aromatic, or polar-with-polarmatches between subject and object residues are added to the scores. Inanother example, quantitative evaluation of sequence homology may beperformed using amino acid substitution matrices such as the BLOSUM62matrix of Henikoff and Henikoff.

An object sequence for the framework region C-terminal to CDR3 sequencecan be selected from the set of known human germline J segments. A Jpeptide sequence is selected by evaluating residue to residue homologyfor each J segment for sequence positions for which CDR3 and J overlap,using the scoring criteria specified for the evaluation of candidate Vgenes as mentioned above. The J gene segment peptide sequence used forsubsequent construction of a converted antibody is chosen from among the25 percent of candidates with the highest score.

As an example, the chimeric variable chain contains at least two CDRsfrom a subject non-human sequence, and framework sequences from acandidate human sequence. In another example, chimeric light chaincontains three CDRs from a subject non-human sequence and frameworksequences from a candidate human sequence. In additional examples, achimeric heavy chain contains at least two CDRs of a subject heavychain, and framework sequence of a candidate human heavy chain, or achimeric heavy chin contains each of the CDRs from the subject heavychain and framework sequences of a candidate human heavy chain. In stillanother example, a chimeric antibody heavy chain contains CDRs 1 and 2from a subject non-human sequence and residues 50-60 for CDR3 andresidues 61-65 of a CDR from the candidate human heavy chain, along withthe framework sequences of the candidate human sequence. In anotherexample, a chimeric heavy chain sequence contains each CDR from thesubject non-human sequence; frameworks sequences 27-30 form the subjectsequence, and the framework sequences from the candidate sequences. Inall cases however, the chimeric antibody molecule contains no more than10 amino acid residues in the framework sequence that differ from thosein the framework sequence of the candidate human variable ration.

When increased affinity of a humanized antibody is desired, residueswithin the CDRs of a converted antibody may be additionally substitutedwith other amino acids. Typically, no more than four amino acid residuesin a CDR are changed, and most typically no more than two residues inthe CDR will be changed, except for heavy chain CDR2, where as many as10 residues may be changed. Changes in affinity can be measured byconventional methods such as those described herein (e.g., Biacore).

The methods of superhumanizing antibodies are described in more detailin U.S. Pat. No. 6,881,557 which is hereby incorporated by reference inits entirety.

Humanized antibodies and antigen-binding fragments can be constructedand produced using conventional techniques known in the art. Inaddition, recombinantly prepared antibodies can often be produced inlarge quantities, particularly when utilizing high level expressionvectors.

Antibodies can be sequenced using conventional techniques known in theart. In one aspect, the amino acid sequences of one or more of the CDRsis inserted into a synthetic sequence of, for example, a human antibody(or antigen-binding fragment thereof) framework to create a humanantibody that could limit adverse side reactions of treating a humanpatient with a non-human antibody. The amino acid sequences of one ormore of the CDRs can also be inserted into a synthetic sequence of, forexample, into a binding protein such as an AVIMER™ to create a constructfor administration to a human patient. Such techniques can be modifieddepending on the species of animal to be treated. For example, forveterinary uses, an antibody, antigen-binding fragment or bindingprotein can be synthesized for administration of a non-human (e.g., aprimate, a cow, a horse, etc.).

In another aspect, using art-recognized techniques such as thoseprovided and incorporated herein, nucleotides encoding amino acidsequences of one or more of the CDRs can inserted, for example, byrecombinant techniques in restriction endonuclease sites of an existingpolynucleotide that encodes an antibody, antigen-binding fragment orbinding protein.

For expression, an expression system is one which utilizes the GS system(Lonza) using a glutamine synthetase gene as the selectable marker.Briefly, a transfection is performed in CHO cells by electroporation(250V) using the GS system (Lonza) using the glutamine synthetase geneas the selectable marker. Wild type CHO cells are grown in DMEM (Sigma)containing 10% dialyzed Fetal Calf Serum (FCS) with 2 mM glutamine.6×10⁷ CHO cells are transfected with 300 μg of linearized DNA byelectroporation. After electroporation the cells are resuspended in DMEMwith glutamine and plated out into 36×96-well plates (50 μl/well), andincubated at 37° C. in 5% CO₂. The following day, 150 μl/well ofselective medium (DMEM without glutamine) is added. After approximately3 weeks the colonies are screened by ELISA (see below) using anirrelevant antibody as a negative control. All colonies producing >20μg/ml are expanded into 24-well plates and then into duplicate T25flasks.

For high level production, the most widely used mammalian expressionsystem is one which utilizes the gene amplification procedure offered bydihydrofolate reductase deficient (“dhfr-”) Chinese hamster ovary cells.The system is well known to the skilled artisan. The system is basedupon the dehydrofolate reductase “dhfr” gene, which encodes the DHFRenzyme, which catalyzes conversion of dehydrofolate to tetrahydrofolate.In order to achieve high production, dhfr-CHO cells are transfected withan expression vector containing a functional DHFR gene, together with agene that encodes a desired protein. In this case, the desired proteinis recombinant antibody heavy chain and/or light chain.

By increasing the amount of the competitive DHFR inhibitor methotrexate(MTX), the recombinant cells develop resistance by amplifying the dhfrgene. In standard cases, the amplification unit employed is much largerthan the size of the dhfr gene, and as a result the antibody heavy chainis co-amplified.

When large scale production of the protein, such as the antibody chain,is desired, both the expression level and the stability of the cellsbeing employed are taken into account. In long term culture, recombinantCHO cell populations lose homogeneity with respect to their specificantibody productivity during amplification, even though they derive froma single, parental clone.

The present application provides an isolated polynucleotide (nucleicacid) encoding an antibody or antigen-binding fragment as describedherein, vectors containing such polynucleotides, and host cells andexpression systems for transcribing and translating such polynucleotidesinto polypeptides.

The present application also provides constructs in the form ofplasmids, vectors, transcription or expression cassettes which compriseat least one polynucleotide as above.

The present application also provides a recombinant host cell whichcomprises one or more constructs as above. A nucleic acid encoding anyantibody or antigen-binding fragments thereof described herein asprovided itself forms an aspect of the present application, as does amethod of production of the antibody or antigen-binding fragmentsthereof described herein which method comprises expression from encodingnucleic acid therefrom. Expression can conveniently be achieved byculturing under appropriate conditions recombinant host cells containingthe nucleic acid. Following production by expression, an antibody orantigen-binding fragment can be isolated and/or purified using anysuitable technique, then used as appropriate.

Specific antibodies, antigen-binding fragments, and encoding nucleicacid molecules and vectors described herein can be provided isolatedand/or purified, e.g., from their natural environment, in substantiallypure or homogeneous form. In the case of nucleic acid, free orsubstantially free of nucleic acid or genes origin other than thesequence encoding a polypeptide with the required function. Nucleic acidcan comprise DNA or RNA and can be wholly or partially synthetic.Methods of purification are well known in the art.

Systems for cloning and expression of a polypeptide in a variety ofdifferent host cells are well known. Suitable host cells includebacteria, mammalian cells, yeast and baculovirus systems. Mammalian celllines available in the art for expression of a heterologous polypeptideinclude Chinese hamster ovary cells, HeLa cells, baby hamster kidneycells, NS0 mouse myeloma cells and many others. A common bacterial hostis E. coli.

The expression of antibodies and antibody fragments in prokaryotic cellssuch as E. coli is well established in the art. For a review, see forexample Plückthun, A. Bio/Technology 9: 545-551 (1991). Expression ineukaryotic cells in culture is also available to those skilled in theart as an option for production of the antibodies and antigen-bindingfragments described herein, see for recent reviews, for example Raff, M.E. (1993) Curr. Opinion Biotech. 4: 573-576; Trill J. J. et al. (1995)Curr. Opinion Biotech 6: 553-560, each of which is which is incorporatedherein by reference in its entirety.

Suitable vectors can be chosen or constructed, containing appropriateregulatory sequences, including promoter sequences, terminatorsequences, polyadenylation sequences, enhancer sequences, marker genesand other sequences as appropriate. Vectors can be plasmids, viral e.g.phage, or phagemid, as appropriate. For further details see, forexample, Molecular Cloning: a Laboratory Manual: 2nd edition, Sambrooket al., 1989, Cold Spring Harbor Laboratory Press. Many known techniquesand protocols for manipulation of nucleic acid, for example inpreparation of nucleic acid constructs, mutagenesis, sequencing,introduction of DNA into cells and gene expression, and analysis ofproteins, are described in detail in Short Protocols in MolecularBiology, Second Edition, Ausubel et al. eds., John Wiley & Sons, 1992.The methods disclosures of Sambrook et al. and Ausubel et al. areincorporated herein by reference in their entirety and are well known inthe art.

Thus, a further aspect provides a host cell containing nucleic acid asdisclosed herein. A still further aspect provides a method comprisingintroducing such nucleic acid into a host cell. The introduction canemploy any available technique. For eukaryotic cells, suitabletechniques can include, for example, calcium phosphate transfection,DEAE Dextran, electroporation, liposome-mediated transfection andtransduction using retrovirus or other virus, e.g., vaccinia or, forinsect cells, baculovirus. For bacterial cells, suitable techniques caninclude, for example, calcium chloride transformation, electroporationand transfection using bacteriophage.

The introduction can be followed by causing or allowing expression fromthe nucleic acid, e.g. by culturing host cells under conditions forexpression of the gene.

In one embodiment, the nucleic acid is integrated into the genome (e.g.chromosome) of the host cell. Integration can be promoted by inclusionof sequences which promote recombination with the genome, in accordancewith standard techniques. Ig enhances can be initialized as needed tomaximize expression.

The present application also provides a method which comprises using aconstruct as stated above in an expression system in order to expressthe antibodies or antigen-binding fragments thereof as above.

The present application also relates to isolated nucleic acids, such asrecombinant DNA molecules or cloned genes, or degenerate variantsthereof, mutants, analogs, or fragments thereof, which encode anantibody or antigen-binding sequence described herein that bindsendoglin.

In one aspect, the present application provides a nucleic acid whichcodes for an antibody or antigen-binding fragment thereof as describedherein which binds endoglin.

In a further embodiment, the full DNA sequence of the recombinant DNAmolecule or cloned gene of an antibody or antigen-binding fragmentdescribed herein can be operatively linked to an expression controlsequence which can be introduced into an appropriate host. Theapplication accordingly extends to unicellular hosts transformed withthe cloned gene or recombinant DNA molecule comprising a DNA sequenceencoding the V_(H) and/or V_(L), or portions thereof, of the antibody.

Another feature is the expression of the DNA sequences disclosed herein.As is well known in the art, DNA sequences can be expressed byoperatively linking them to an expression control sequence in anappropriate expression vector and employing that expression vector totransform an appropriate unicellular host.

Such operative linking of a DNA sequence to an expression controlsequence, of course, includes, if not already part of the DNA sequence,the provision of an initiation codon, ATG, in the correct reading frameupstream of the DNA sequence.

Polynucleotides and vectors can be provided in an isolated and/or apurified form (e.g., free or substantially free of polynucleotides oforigin other than the polynucleotide encoding a polypeptide with therequired function). As used herein, “substantially pure,” and“substantially free” refer to a solution or suspension containing lessthan, for example, about 20% or less extraneous material, about 10% orless extraneous material, about 5% or less extraneous material, about 4%or less extraneous material, about 3% or less extraneous material, about2% or less extraneous material, or about 1% or less extraneous material.

A wide variety of host/expression vector combinations can be employed inexpressing the DNA sequences of this invention. Useful expressionvectors, for example, can consist of segments of chromosomal,non-chromosomal and synthetic DNA sequences. Suitable vectors include,but are not limited to, derivatives of SV40 and known bacterialplasmids, e.g., E. coli plasmids col E1, Pcr1, Pbr322, Pmb9 and theirderivatives, plasmids such as RP4; phage DNAs, e.g., the numerousderivatives of phage λ, e.g., NM989, and other phage DNA, e.g., M13 andfilamentous single stranded phage DNA; yeast plasmids such as the 2uplasmid or derivatives thereof; vectors useful in eukaryotic cells, suchas vectors useful in insect or mammalian cells; vectors derived fromcombinations of plasmids and phage DNAs, such as plasmids that have beenmodified to employ phage DNA or other expression control sequences; andthe like.

Also provided herein is a recombinant host cell which comprises one ormore polynucleotide constructs. A polynucleotide encoding an antibody orantigen-binding fragment as provided herein forms an aspect of thepresent application, as does a method of production of the antibody orantigen-binding fragment which method comprises expression from thepolynucleotide. Expression can be achieved, for example, by culturingunder appropriate conditions recombinant host cells containing thepolynucleotide. An antibody or antigen-binding fragment can then beisolated and/or purified using any suitable technique, and used asappropriate.

Any of a wide variety of expression control sequences—sequences thatcontrol the expression of a DNA sequence operatively linked to it—can beused in these vectors to express the DNA sequences. Such usefulexpression control sequences include, for example, the early or latepromoters of SV40, CMV, vaccinia, polyoma or adenovirus, the lac system,the trp system, the TAC system, the TRC system, the LTR system, themajor operator and promoter regions of phage λ, the control regions offd coat protein, the promoter for 3-phosphoglycerate kinase or otherglycolytic enzymes, the promoters of acid phosphatase (e.g., Pho5), thepromoters of the yeast-mating factors, and other sequences known tocontrol the expression of genes of prokaryotic or eukaryotic cells ortheir viruses, and various combinations thereof.

Systems for cloning and expression of a polypeptide in a variety ofdifferent host cells are well known. Suitable host cells includebacteria, mammalian cells, yeast and baculovirus systems. Mammalian celllines available in the art for expression of a heterologous polypeptideinclude Chinese hamster ovary (CHO) cells, HeLa cells, baby hamsterkidney cells, NS0 mouse myeloma cells and many others. A common,bacterial host can be, for example, E. coli.

The expression of antibodies or antigen-binding fragments in prokaryoticcells, such as E. coli, is well established in the art. For a review,see for example Plückthun, A. Bio/Technology 9: 545-551 (1991).Expression in eukaryotic cells in culture is also available to thoseskilled in the art (Raff, M. E. (1993) Curr. Opinion Biotech. 4:573-576; Trill J. J. et al. (1995) Curr. Opinion Biotech 6: 553-560).

A wide variety of unicellular host cells are also useful in expressingthe DNA sequences. These hosts include well-known eukaryotic andprokaryotic hosts, such as strains of E. coli, Pseudomonas, Bacillus,Streptomyces, fungi such as yeasts, and animal cells, such as CHO,YB/20, NS0, SP2/0, R1.1, B-W and L-M cells, African Green Monkey kidneycells (e.g., COS 1, COS 7, BSC1, BSC40, and BMT10), insect cells (e.g.,Sf9), and human cells and plant cells in tissue culture.

It will be understood that not all vectors, expression control sequencesand hosts will function equally well to express the DNA sequences.Neither will all hosts function equally well with the same expressionsystem. However, one skilled in the art will be able to select theproper vectors, expression control sequences, and hosts without undueexperimentation to accomplish the desired expression without departingfrom the scope of this application. For example, in selecting a vector,the host must be considered because the vector must function in it. Thevector's copy number, the ability to control that copy number, and theexpression of any other proteins encoded by the vector, such asantibiotic markers, will also be considered. One of ordinary skill inthe art can select the proper vectors, expression control sequences, andhosts to accomplish the desired expression without departing from thescope of this application. For example, in selecting a vector, the hostis considered because the vector functions in it. The vector's copynumber, the ability to control that copy number, and the expression ofany other proteins encoded by the vector, such as antibiotic markers,can also be considered.

The present application also provides constructs in the form ofplasmids, vectors, transcription or expression cassettes as describedelsewhere herein which comprise at least one polynucleotide as above.Suitable vectors can be chosen or constructed, containing appropriateregulatory sequences, including promoter sequences, terminatorsequences, polyadenylation sequences, enhancer sequences, selectablemarkers and other sequences as appropriate. Vectors can be plasmids,viral e.g., phage, phagemid, etc., as appropriate. For further detailssee, for example, Molecular Cloning: a Laboratory Manual: 2nd edition,Sambrook et al., 1989, Cold Spring Harbor Laboratory Press. Many knowntechniques and protocols for manipulation of nucleic acid, for examplein preparation of nucleic acid constructs, mutagenesis, sequencing,introduction of DNA into cells and gene expression, and analysis ofproteins, are described in detail in Short Protocols in MolecularBiology, Second Edition, Ausubel et al. eds., John Wiley & Sons, 1992.The methods and disclosures of Sambrook et al. and Ausubel et al. areincorporated herein by reference.

In selecting an expression control sequence, a variety of factors willnormally be considered. These include, for example, the relativestrength of the system, its controllability, and its compatibility withthe particular DNA sequence or gene to be expressed, particularly asregards potential secondary structures. Suitable unicellular hosts willbe selected by consideration of, e.g., their compatibility with thechosen vector, their secretion characteristics, their ability to foldproteins correctly, and their fermentation requirements, as well as thetoxicity to the host of the product encoded by the DNA sequences to beexpressed, and the ease of purification of the expression products.

A further aspect provides a host cell containing one or morepolynucleotides as disclosed herein. Yet a further aspect provides amethod of introducing such one or more polynucleotides into a host cell,any available technique. For eukaryotic cells, suitable techniques caninclude, for example, calcium phosphate transfection, DEAEDextran,electroporation; liposome-mediated transfection and transduction usingretrovirus or other virus (e.g. vaccinia) or, for insect cells,baculovirus. For bacterial cells, suitable techniques can include, forexample calcium chloride transformation, electroporation andtransfection using bacteriophages.

The introduction can be followed by causing or allowing expression fromthe one or more polynucleotides, e.g. by culturing host cells underconditions for expression of one or more polypeptides from one or morepolynucleotides. Inducible systems can be used and expression induced byaddition of an activator.

In one embodiment, the polynucleotides can be integrated into the genome(e.g., chromosome) of the host cell. Integration can be promoted byinclusion of sequences which promote recombination with the genome, inaccordance with standard techniques. In another embodiment, the nucleicacid is maintained on an episomal vector in the host cell.

Methods are provided herein which include using a construct as statedabove in an expression system in order to express a specificpolypeptide.

Considering these and other factors, a person skilled in the art will beable to construct a variety of vector/expression control sequence/hostcombinations that will express the DNA sequences on fermentation or inlarge scale animal culture.

A polynucleotide encoding an antibody, antigen-binding fragment, or abinding protein can be prepared recombinantly/synthetically in additionto, or rather than, cloned. The polynucleotide can be designed with theappropriate codons for the antibody, antigen-binding fragment, or abinding protein. In general, one will select preferred codons for anintended host if the sequence will be used for expression. The completepolynucleotide can be assembled from overlapping oligonucleotidesprepared by standard methods and assembled into a complete codingsequence. See, e.g., Edge, Nature, 292:756 (1981); Nambair et al.,Science, 223:1299 (1984); Jay et al., J. Biol. Chem., 259:6311 (1984).

A general method for site-specific incorporation of unnatural aminoacids into proteins is described in Christopher J. Noren, Spencer J.Anthony-Cahill, Michael C. Griffith, Peter G. Schultz, Science,244:182-188 (April 1989). This method can be used to create analogs withunnatural amino acids.

As mentioned above, a DNA sequence encoding an antibody orantigen-binding fragment thereof can be prepared synthetically ratherthan cloned. The DNA sequence can be designed with the appropriatecodons for the antibody or antigen-binding fragment amino acid sequence.In general, one will select preferred codons for the intended host ifthe sequence will be used for expression. The complete sequence isassembled from overlapping oligonucleotides prepared by standard methodsand assembled into a complete coding sequence. See, e.g., Edge, Nature,292:756 (1981); Nambair et al., Science, 223:1299 (1984); Jay et al., J.Biol. Chem., 259:6311 (1984), each of which is which is incorporatedherein by reference in its entirety.

C. In silico Analysis of Immunogenicity

If needed, an antibody or an antigen binding fragment thereof describedherein can be assessed for immunogenicity and, as needed, be deimmunized(i.e. the antibody is made less immuno reactive by altering one or moreT cell epitopes). Analysis of immunogenicity and T-cell epitopes presentin the humanized anti-endoglin antibodies and antigen-binding fragmentsdescribed herein can be carried out via the use of software and specificdatabases. Exemplary software and databases include iTope™ developed byAntitope of Cambridge, England. iTope™ is an in silico technology foranalysis of peptide binding to human MHC class II alleles.

The iTope™ software predicts peptide binding to human MHC class IIalleles and thereby provides an initial screen for the location of such“potential T cell epitopes.” iTope™ software predicts favorableinteractions between amino acid side chains of a peptide and specificbinding pockets within the binding grooves of 34 human MHC class IIallelles. The location of key binding residues is achieved by the insilico generation of 9mer peptides that overlap by one amino acidspanning the test antibody variable region sequence. Each 9mer peptidecan be tested against each of the 34 MHC class II allotypes and scoredbased on their potential “fit” and interactions with the MHC class IIbinding groove. Peptides that produce a high mean binding score (>0.55in the iTope™ scoring function) against >50% of the MHC class II allelesare considered as potential T cell epitopes. In such regions, the core 9amino acid sequence for peptide binding within the MHC class II grooveis analyzed to determine the MHC class II pocket residues (P1, P4, P6,P7 and P9) and the possible T cell receptor (TCR) contact residues (P-1,P2, P3, P5, P8).

After identification of any T-cell epitopes, amino acid residue changes,substitutions, additions, and/or deletions can be introduced to removethe identified T-cell epitope. Such changes can be made so as topreserve antibody structure and function while still removing theidentified epitope. Exemplary changes can include, but are not limitedto, conservative amino acid changes.

Techniques exploiting soluble complexes of recombinant MHC molecules incombination with synthetic peptides have come into use. These reagentsand procedures may be used to identify the presence of T-cell clonesfrom peripheral blood samples from human or experimental animal subjectsthat are able to bind particular MHC-peptide complexes and are notadapted for the screening multiple potential epitopes to a widediversity of MHC allotypes.

Biological assays of T-cell activation remain the best practical optionto providing a reading of the ability of a test peptide/protein sequenceto evoke an immune response. Examples of this kind of approach includethe use of T-cell proliferation assays to the bacterial proteinstaphylokinase, followed by epitope mapping using synthetic peptides tostimulate T-cell lines. Similarly, T-cell proliferation assays usingsynthetic peptides of the tetanus toxin protein have resulted indefinition of immunodominant epitope regions of the toxin. In oneembodiment, T-cell epitopes in a test protein may be determined usingisolated sub-sets of human immune cells, promoting their differentiationin vitro and culture of the cells in the presence of synthetic peptidesof interest and measurement of any induced proliferation in the culturedT-cells. Other techniques may also be used. Such a technique involvescareful application of cell isolation techniques and cell culture withmultiple cytokine supplements to obtain the desired immune cell sub-sets(dendritic cells, CD4+ and or CD8+ T-cells). In another embodiment, thepresence of T cell epitopes in an antibody may be determined by addingthe antibody to isolated sub-sets of human immune cells, and assessingtheir differentiation in vitro and measuring any induced proliferationin the cultured T cells.

In silico techniques to define MHC class II ligands for multipleproteins of therapeutic interest may also be utilized. However, forreasons such as the requirement for proteolytic processing and otherphysiologic steps leading to the presentation of immunogenic peptides invivo, a sub-set of the entire repertoire of peptides definable bycomputer-based schemes may have ultimate biological relevance. Thus, exvivo human T-cell activation assays may be used to identify the regionswithin the protein sequence of a polypeptide that are able to supportT-cell activation and are thereby most biologically relevant to theproblem of immunogenicity in this protein. As used herein, “T-cellepitope” refers to an amino acid sequence which is able to bind MHCclass II, able to stimulate T-cells and/or also to bind (withoutnecessarily measurably activating) T-cells in complex with MHC class II.

According to a method disclosed herein, synthetic peptides or wholeantibodies are tested for their ability to evoke a proliferativeresponse in human T-cells cultured in vitro. The T-cells are presentwithin a peripheral blood mononuclear cell (PBMC) layer readilyobtainable by well known means from whole blood samples. Moreover, thePBMC preparation contains physiological ratios of T-cells and antigenpresenting cells and is, therefore, a good source of materials withwhich to conduct a surrogate immune reaction in vitro. In the operationof such an assay, a stimulation index approaching or exceeding 2.0 is auseful measure of induced proliferation. However, the stimulation indexmay be different depending upon the antibody, or antigen-bindingfragment thereof, and may be established with reference to a baselinefor each antibody, or antigen-binding fragment thereof, andcorresponding peptide library. In one example of such testing, thestimulation index (SI) may be conventionally derived by division of theproliferation score (e.g. counts per minute of radioactivity if usingfor example ³H-thymidine incorporation) measured to the test peptide bythe score measured in cells not contacted with a test peptide. Peptideswhich evoke no response may give a SI=1.0 although SI values in therange 0.8-1.2 may also be unremarkable. A number of technical procedurescan be built into the operation of such assays in order to ensureconfidence in the recorded scores. Typically all determinations are madeat least in triplicate and the mean score may be computed.

Where a computed SI=>2.0, individual scores of the triplicate can beexamined for evidence of outlying data. Test peptides are contacted withcells in at least two different concentrations and the concentrationswould typically span a minimum two-fold concentration difference. Such aconcentration range provides an off-set to the kinetic dimension to theassay and may be useful where a single time point determination, forexample at day plus 7, is being conducted. In some assays, multiple timecourse determinations may be conducted and these too may be made usingpeptide immunogen provided at a minimum of two different concentrations.Similarly the inclusion of control peptides for which there isexpectation that the majority of PBMC donor samples will be responsivemay be included in each assay plate. The influenza haemagglutininpeptide 307-309, sequence PKYVKQNTLKLA (SEQ ID NO: 104); and theChlamydia HSP 60 peptide sequence KVVDQIKKISKPVQH (SEQ ID NO: 105) areexamples of control peptides to be used in such an assay. Alternatively,or in addition, assays could also use a potent whole protein antigen,such as hemocyanin from Keyhole Limpet, to which all PBMC samples wouldbe expected to exhibit an SI significantly greater than 2.0. Othercontrol antigens for such use will be well-known in the art.

The methods disclosed herein can provide an epitope map of antibodies,or antigen-binding fragments thereof, where the map has relevance to awide spectrum of possible MHC allotypes. The map may be sufficientlyrepresentative to allow the design or selection of a modified proteinfor which the ability of the protein to evoke a T-cell driven immuneresponse may be eliminated or at least ameliorated for the majority ofpatients to whom the protein is likely to be administered. Ameliorationcan refer to a reduction in an immune response (i.e., reducedimmunogenicity) compared to an unmodified protein (e.g. about 1.5 foldless, about 2 fold less, about 5 fold less, about 10 fold less, about 20fold less, about 50 fold less, about 100 fold less, about 200 fold less,about 500 fold less or more, or any range therein). Alternatively,antibodies, or antigen-binding fragments thereof, with reducedimmunogenicity can refer to a percent reduction in its ability to elicitan immune response compared to an unmodified protein (e.g. about 1%less, about 2% less, about 3% less, about 4% less, about 5% less, about10% less, about 20% less, about 50% less, about 100% less, and any rangetherein). Accordingly in the practice of the screening process, PBMCderived T-cells from naive donors are collected from a pool of donors ofsufficient immunological diversity to provide a sample of at leastgreater than 90% of the MHC class II repertoire (HLA-DR) extant in thehuman population. Where a naive T-cell response is to be detected to agiven synthetic peptide (or antibody), the peptide (or antibody) inpractice is contacted with PBMC preparations derived from multipledonors in isolation; the numbers of donors (or “donor pool” size), isfor practical purposes not likely to be less than 20 unrelatedindividuals and all samples in the donor pool may be pre-selectedaccording to their MHC class II haplotype.

As used herein, the term “naive donor” refers to a subject that has notbeen previously exposed to antibodies, or antigen-binding fragmentsthereof, described herein either environmentally, by vaccination, or byother means such as, for example, blood transfusions.

When screening for T-cell epitopes, T-cells can be provided from aperipheral blood sample from a multiplicity of different healthy donorsbut who have not been in receipt of the protein therapeutically. Ifneeded, patient blood samples can be tested for the presence of aparticular polypeptide using conventional assays such as an ELISA whichuses antibodies to identify the presence or absence of one or morepolypeptides. The assay is conducted using PBMC cultured in vitro usingconventional procedures known in the art and involves contacting thePBMC with synthetic peptide species representative of the protein ofinterest (i.e. a library), or a whole protein, such as an antibody andfollowing a suitable period of incubation, measurement of induced T cellactivation such as cellular proliferation. Measurement can be by anysuitable means and may, for example, be conducted using H³-thymidineincorporation whereby the accumulation of H³ into cellular material isreadily measured using laboratory instruments. The degree of cellularproliferation for each combination of PBMC sample and synthetic peptideor whole protein can be examined relative to that seen in an untreatedPBMC sample. Reference may also be made to the proliferative responseseen following treatment with a peptide or peptides or whole proteinsfor which there is an expected proliferative effect. In this regard, itis advantageous to use a peptide or whole protein with known broad MHCrestriction and especially peptide epitopes with MHC restriction to theDP or DQ isotypes, although the invention is not limited to the use ofsuch restricted peptides or proteins. Such peptides have been describedabove, for example, with respect to influenza haemagglutinin andchlamydia HSP60.

In one non-limiting example, T-cell epitopes are mapped and subsequentlymodified using the methods described herein. To facilitate assembly ofan epitope map, a library of synthetic peptides is produced. Each of thepeptides is 15 amino acid residues in length and each overlapped thenext peptide in the series by 12 amino acid residues; i.e. eachsuccessive peptide in the series incrementally added a further 3 aminoacids to the analysis. In this way, any given adjacent pair of peptidesmapped 18 amino acids of contiguous sequence. One method for defining aT-cell map using naive T-cell assays is illustrated in the Examplesbelow. Each of the peptides identified via the method to define a T-cellmap are suggested to be able to bind MHC class II and engage at leastone cognate TCR with sufficient affinity to evoke a proliferative burstdetectable in the assay system.

In another non-limiting example, the potential of an antibody to beprocessed to generate T-cell epitopes that bind MHC class II and engageat least one cognate TCR with sufficient affinity to evoke aproliferative burst detectable in the assay system is assessed.

The molecules described herein can be prepared in any of several waysincluding the use of recombinant methods. The protein sequences andinformation provided herein can be used to deduce a polynucleotide (DNA)encoding an amino acid sequence. This can be achieved for example usingcomputer software tools such as the DNAstar software suite [DNAstar Inc,Madison, Wis., USA] or similar. Any such polynucleotide encoding thepolypeptides or significant homologues, variants, truncations,elongations, or further modifications thereof, are contemplated herein.

Provided herein are methods of mapping (identifying) T-cell epitopes andmodifying the epitopes such that the modified sequence reduces(partially or completely) induction of a T-helper response. Modificationincludes amino acid substitutions, deletions, or insertion made incodons of a polynucleotide encoding modified polypeptides to affectsimilar changes. Codons encoding amino acid residues are well known inthe art. It is possible to use recombinant DNA methods to achievedirected mutagenesis of the target sequences and many such techniquesare available, described herein, and known in the art such as describedabove. In general, the technique of site-specific mutagenesis is wellknown. Briefly, a bacteriophage vector that produces a single strandedtemplate for oligonucleotide directed PCR mutagenesis is employed. Phagevectors (e.g. M13) are commercially available and their use is generallywell known in the art. Similarly, double stranded plasmids are alsoroutinely employed in site directed mutagenesis, which eliminates thestep of transferring the polynucleotide of interest from a phage to aplasmid. Synthetic oligonucleotide primers bearing the desired mutatedsequence can be used to direct the in vitro synthesis of modified(desired mutant) DNA from this template and the heteroduplex DNA is usedto transform competent E. coli for the growth selection andidentification of desired clones. Alternatively, a pair of primers canbe annealed to two separate strands of a double stranded vector tosimultaneously synthesize both corresponding complementary strands withthe desired mutation(s) in a PCR reaction.

In one embodiment, the Quick Change site-directed mutagenesis methodusing plasmid DNA templates may be employed. PCR amplification of theplasmid template containing the insert target gene of insert is achievedusing two synthetic oligonucleotide primers containing the desiredmutation. The oligonucleotide primers, each complementary to oppositestrands of the vector, are extended during temperature cycling bymutagenesis-grade Pfu Turbo DNA polymerase. On incorporation of theoligonucleotide primers, a mutated plasmid containing staggered nicks isgenerated. Amplified un-methylated products are treated with Dpn I todigest methylated parental DNA template and select for the newlysynthesized DNA containing mutations. Since DNA isolated from most E.coli strains is dam methylated, it is susceptible to Dpn I digestion,which is specific for methylated and hemimethylated DNA. The reactionproducts are transformed into high efficiency strains of E. coli toobtain plasmids containing the desired modifications. Additional methodsfor introducing amino acid modifications into a polypeptide are wellknown in the art and can also be used herein.

Suitable modifications to a protein may include amino acid substitutionof particular residues or combinations of residues. For the eliminationof T-cell epitopes, amino acid substitutions are made at appropriatepoints or amino acid residues within an amino acid sequence predicted toachieve reduction or elimination of the activity of the T-cell epitope.In practice, an appropriate point or amino acid residue will preferablyequate to an amino acid residue binding within one of the pocketsprovided within the MHC class II binding groove. Such modifications mayalter binding within the first pocket of the cleft at the so-called “P1”or “P1 anchor” position of the peptide. The quality of bindinginteraction between the P1 anchor residue of the peptide and the firstpocket of the MHC class II binding groove is recognized as being a majordeterminant of overall binding affinity for the whole peptide. Anappropriate substitution at this position of the amino acid sequencewill generally incorporate an amino acid residue less readilyaccommodated within the pocket (e.g., substitution to a more hydrophilicresidue). Amino acid residues in the peptide at positions equating tobinding within other pocket regions within the MHC binding cleft arealso considered and fall under the scope of the present.

It is understood that single amino acid modifications within a givenpotential T-cell epitope represent one route by which one or more T-cellepitopes may be eliminated. Combinations of modifications within asingle epitope may be contemplated and can be appropriate whereindividually defined epitopes are in overlap with each other. Moreover,amino acid modifications (either singly within a given epitope or incombination within a single epitope) may be made at positions notequating to the “pocket residues” with respect to the MHC class IIbinding groove, but at any point within the amino acid sequence.Modifications may be made with reference to a homologous structure orstructural method produced using in silico techniques known in the artand described herein may be based on known structural features of thepolypeptide. A change (modification) may be contemplated to restorestructure or biological activity of the variant molecule. Suchcompensatory changes and changes may also include deletion or addition(insertion) of particular amino acid residues from a polypeptide.Additionally, modifications can be made that alter the structure and/orreduce the biological activity of the molecule and also eliminate aT-cell epitope, thus reducing the immunogenicity of the molecule. Alltypes of modifications are contemplated herein.

An additional means of removing epitopes from protein molecules is theconcerted use of a naive T-cell activation assay scheme as outlinedherein together with an in silico tool developed according to the schemedescribed in WO 02/069232 which is also incorporated fully herein byreference. The software simulates the process of antigen presentation atthe level of the polypeptide-MHC class II binding interaction to providea binding score for any given polypeptide sequence. Such a score isdetermined for many of the predominant MHC class II allotypes extant inthe population. As this scheme is able to test any polypeptide sequence,the consequences of amino acid substitutions additions or deletions withrespect to the ability of a polypeptide to interact with a MHC class IIbinding groove can be predicted. Consequently new sequence compositionscan be designed which contain reduced numbers of amino acids able tointeract with a MHC class II and thereby function as immunogenic T-cellepitopes. Where the biological assay using any one given donor samplecan assess binding to a maximum of four DR allotypes, the in silicoprocess can test a same polypeptide sequence using >40 allotypessimultaneously. In practice this approach is able to direct the designof new sequence variants which are altered in their ability to interactwith multiple MHC allotypes. As will be clear to one in the art,multiple alternative sets of substitutions could be arrived at whichachieve the objective of removing undesired epitopes. The resultingsequences would however be recognized to be closely homologous with thespecific compositions disclosed herein and therefore fall within thescope of the present application.

A combined approach of using an in silico tool for the identification ofMHC class II ligands and design of sequence analogues lacking MHC classII ligands, in concert with epitope mapping and re-testing optionallyusing biologically based assays of T-cell activation is an additionalmethod and embodiment of the present application. The general methodaccording to this embodiment comprises the following steps:

i) use of naive T-cell activation assays and synthetic peptidescollectively encompassing the protein sequence of interest to identifyepitope regions capable of activating T-cells;ii) use of a computational scheme simulating the binding of the peptideligand with one or more MHC allotypes to analyze the epitope regionsidentified in step (i) and thereby identify MHC class II ligands withinthe epitope region;iii) use of a computational scheme simulating the binding of the peptideligand with one or more MHC allotypes to identify sequence analogues ofthe MHC ligands encompassed within the epitope region(s) which no longerbind MHC class II or bind with lowered affinity to a lesser number ofMHC allotypes and optionally,iv) use of naive T-cell activation assays and synthetic peptidesencompassing entirely or in collection encompassing the epitope regionsidentified within the protein of interest and testing the sequenceanalogues in naive T-cell activation assay in parallel with thewild-type (parental) sequences.

In one embodiment, a method of making a modified antibody, orantigen-binding fragment thereof, exhibiting reduced immunogenicitycompared to an unmodified antibody, or antigen-binding fragment thereof,comprises identifying at least one T-cell epitope within the amino acidsequence of a antibody, or antigen-binding fragment thereof, andmodifying at least one amino acid residue within at least one identifiedT-cell epitope.

In another embodiment, a modified antibody, or antigen-binding fragmentthereof, exhibiting reduced immunogenicity compared to an unmodifiedantibody, or antigen-binding fragment thereof, is produced by a processof identifying at least one T-cell epitope within the amino acidsequence of a antibody, or antigen-binding fragment thereof, andmodifying at least one amino acid residue within at least one identifiedT-cell epitope.

In yet another embodiment, a method of selecting a modified antibody, orantigen-binding fragment thereof, that exhibits reduced immunogenicitycompared to an unmodified antibody, or antigen-binding fragment thereof,comprises identifying at least one T-cell epitope within the amino acidsequence of a antibody, or antigen-binding fragment thereof, modifyingat least one amino acid residue within at least one identified T-cellepitope, and selecting a modified antibody, or antigen-binding fragmentthereof, that exhibits reduced immunogenicity compared to an unmodifiedantibody, or antigen-binding fragment thereof.

T-cell epitopes described herein can be further characterized by theregions of the epitope. Such regions include the epitope core, theN-terminus and the C-terminus. As used herein “epitope core” refers tothe core 9-mer amino acid sequences of the T-cell epitopes. The epitopecore can further include 0, 1, 2, or 3 amino acid residues adjacent tothe core 9-mer amino acid sequence on the N-terminus and/or theC-terminus. Thus the epitope core, in certain embodiments, can range inlength from about 9 amino acids up to about 15 amino acids.

As used herein, “N-terminus” refers to the amino acids adjacent to theN-terminus of the epitope core and includes at least 1, 2, 3, 4, 5, 6,7, 8 or 9 amino acids adjacent to and upstream of the N-terminus of theepitope core.

As used herein, “C-terminus” refers to the amino acids adjacent to theC-terminus of the epitope core and includes at least 1, 2, 3, 4, 5, 6,7, 8, or 9 amino acids adjacent to and downstream of the C-terminus ofthe epitope core.

In one embodiment, a modified antibody, or antigen-binding fragmentthereof, contains one or more modifications.

In one embodiment, a modified antibody, or antigen-binding fragmentthereof, contains two modifications.

In one embodiment, a modified antibody, or antigen-binding fragmentthereof, contains three modifications.

In one embodiment, a modified antibody, or antigen-binding fragmentthereof, contains four modifications.

In one embodiment, a modified antibody, or antigen-binding fragmentthereof, contains five modifications.

In one embodiment, a modified antibody, or antigen-binding fragmentthereof, contains six modifications.

In one embodiment, a modified antibody, or antigen-binding fragmentthereof, contains seven modifications.

In one embodiment, a modified antibody, or antigen-binding fragmentthereof, contains eight modifications.

In one embodiment, a modified antibody, or antigen-binding fragmentthereof, contains nine modifications.

In one embodiment, a modified antibody, or antigen-binding fragmentthereof, contains ten modifications.

In one embodiment, a modified antibody, or antigen-binding fragmentthereof, contains up to twenty modifications.

Provided herein is an antibody, or antigen-binding fragment thereof,comprising a light chain variable region having an amino acid sequenceset forth as SEQ ID NO: 93-(VK1AA) and a heavy chain variable regionhaving an amino acid sequence set forth as SEQ ID NO: 89 (VH1A2).

Provided herein is an antibody, or antigen-binding fragment thereof,comprising a heavy chain variable region having an amino acid sequenceset forth as any one of SEQ ID NOS: 88, 89, 90, 91 and 92.

Provided herein is an antibody, or antigen-binding fragment thereof,comprising a light chain variable region having an amino acid sequenceset forth as any one of SEQ ID NOS: 93, 94, 95, 96, 97, 100, 102, and103.

Provided herein is an antibody, or antigen-binding fragment thereof,that binds endoglin, comprising a heavy chain variable region having anamino acid sequence set forth as SEQ ID NO: 89 and a light chainvariable region having an amino acid sequence set forth as SEQ ID NO:93, wherein:

(i) the heavy chain variable region further comprises one or moremodifications selected from the group consisting of a substitution ofglycine (G) by alanine (A) or serine (S) at position 49; a substitutionof alanine (A) by isoleucine (I) at position 51; a substitution oflysine (K) by arginine (R) or asparagine (O) at position 52b; asubstitution of leucine (L) by valine (V) at position 78 utilizing theKabat numbering system; and

(ii) the light chain variable region further comprises one or moremodifications selected from the group consisting of a substitution ofmethionine (M) by leucine (L) at position 4; a substitution of alanine(A) by valine (V) at position 19; a substitution of threonine (T) byserine (S) at position 22; a substitution of alanine (A) by isoleucine(I) at position 48; and a substitution of threonine (T) by serine (S) atposition 51 utilizing the Kabat numbering system

Provided herein is an antibody, or antigen-binding fragment thereofcomprising a heavy chain variable region having an amino acid sequenceset forth as SEQ ID NO: 88, 89, 90, 91 and 92; and a light chainvariable region having an amino acid sequence set forth as SEQ ID NO:93, 95, 96, 97, 100, 102, or 103.

In addition to the aforementioned examples and embodiments, a modifiedantibody, or antigen-binding fragment thereof, with one or more aminoacid modifications in one or more T-cell epitopes are contemplatedherein. In one non-limiting example, provided herein are antibodies, orantigen-binding fragments thereof, having at least one modification inat least one T-cell epitope. In another non-limiting example, providedherein are antibodies, or antigen-binding fragments thereof, having atleast one amino acid modification in 1, 2, 3, 4, 5, 6, or 7 of theT-cell epitopes described herein. Additional non-limiting examplesinclude antibodies, or antigen-binding fragments thereof, having morethan one amino acid modification in more than one T-cell epitope. Anycombination of the amino acid modifications in any number of theantibodies, or antigen-binding fragments thereof, T-cell epitopesdescribed above are contemplated herein.

T-Cell Epitopes and Allotype Frequency

Individual epitopes found within antigens can be preferentiallypresented by specific MHC class II allotypes, and similarly otherspecific epitopes within the same antigen may not be presented on MHCclass II molecules at all. Such associations of particular epitopes withspecific MCH class II molecules have been shown to depend upon the MHCclass II allotype of the individual. The association of a specificepitope with a specific allotype can also be considered when modifyingantibodies, or antigen-binding fragments thereof, for the removal ofT-cell epitopes. Such considerations can allow for the highly specificmodification of an antibody, or antigen-binding fragment thereof, forspecific allotypes (e.g. for specific populations of subjects havingcertain MHC class II allotypes). The MHC class II allotype of a subjector subjects can be easily determined by genotyping methods known in theart, and the association of T-cell epitopes with the given allotype thuseasily identified, for consideration in modification of antibodies, orantigen-binding fragments thereof, tailored to that allotype.Identification of associations between T-cell epitopes and MHC class IIallotypes are described in more detail in the examples below.Contemplated herein are modified antibodies, or antigen-bindingfragments thereof, that have T-cell epitope modifications tailored tothe MHC class II associations identified for the given epitopes.

D. Anti-Endoglin Antibodies

Simultaneous incorporation of all of the FR and/or CDR encoding nucleicacids and all of the selected amino acid position changes can beaccomplished by a variety of methods known to those skilled in the art,including for example, recombinant and chemical synthesis. For example,simultaneous incorporation can be accomplished by, for example,chemically synthesizing the nucleotide sequence for the acceptorvariable region, fused together with the donor CDR encoding nucleicacids, and incorporating at the positions selected for harboringvariable amino acid residues a plurality of corresponding amino acidcodons.

Provided herein are antibodies and antigen-binding fragments thereofthat bind to endoglin. Also provided are antibodies and antigen-bindingfragments thereof that bind endoglin and inhibit (partially or fully) ormanage/treat (partially or fully) angiogenesis/neovascularization,dilation of small vessels, and/or diseases associated with excessiveangiogenesis. Similarly, inhibition of endoglin function (e.g.signaling, binding, activation, and the like) is also included withinthe meaning of inhibiting or binding endoglin. In yet anotherembodiment, an antibody or antigen-binding fragment inhibitsangiogenesis by binding to endoglin. The application also provides celllines which can be used to produce the antibodies, methods for producingthe cell lines, methods for expressing antibodies or antigen-bindingfragments and purifying the same.

One can recognize that the antibodies and antigen-binding fragmentsthereof that specifically bind endoglin generated using the methodsdescribed herein can be tested using the assays provided herein or knownin the art for the ability to bind to endoglin using conventionalmethods including, but not limited to, ELISA. Affinity of antibodiesdescribed herein can also be determined using conventional methodsincluding, but not limited to, Biacore or surface plasmon resonance.

The antibodies and antigen binding fragments thereof described hereinwere constructed by humanization of the V_(H) and V_(L) sequences of theTRC105 antibody. To accomplish this humanization, a 3-dimensional modelof the V_(H) and V_(L) chains of TRC105 was created and analyzed. TheV_(H) and V_(L) sequences were then compared individually to a databaseof human germline sequences, from which human V_(H) and V_(L) sequenceswere chosen based on their homology to the V_(H) and V_(L) sequences ofTRC105. The human V_(L) sequence chosen for humanization was O2/O12(VK1-39) (SEQ ID NO. 2). O2/O12 has a sequence identity with TRC105 of65% and the gene is highly expressed in the human germline repertoire.The human V_(H) sequence chosen for humanization was VH3-15 (SEQ ID NO.40). VH3-15 has sequence identity with TRC105 of 70% and is expressedwith reasonable frequency in the human germline repertoire. The aminoacid positions which were different between TRC105 and the humansequences were examined in the 3D model of TRC105 to determine whichsubstitutions would be considered for modification. Amino acid selectioncriteria based on the 3D model analysis included, but was not limitedto, for example, steric effects related to the amino acid, relativecharge of the amino acid, and the location of the amino acid within thevariable heavy and/or light chains. The identified and proposedsubstitutions for the human framework regions are incorporated into theO2 and VH3-15 human framework regions, and the CDRs of TRC105 aregrafted into the corresponding O2 and VH3-15 human framework regionsresulting in a multitude of humanized antibodies or antigen-bindingfragments. Additionally, the FR-4 of the light chain is derived fromhuman J germline sequence JH4. Similarly, the FR-4 of the heavy chain isderived from human J germline sequence JH4.

Described herein are humanized antibodies and antigen-binding fragmentsthat bind endoglin. Also described herein are humanized antibodies andantigen-binding fragments that bind endoglin and inhibit angiogenesis.The antibodies and antigen-binding fragments described herein weregenerated as described above.

Antibodies and antigen-binding fragments thereof can have a variableheavy (V_(H)) chain, a variable light (V_(L)) chain, both, or bindingportions thereof. In one embodiment, the V_(H) chain has an amino acidsequence set forth as any of SEQ ID NOS: 41-43, or a binding portionthereof. Such V_(H) chains can have framework regions sequences setforth as any of SEQ ID NOS: 44-62. In another embodiment, the V_(L)chain has an amino acid sequence set forth as any of SEQ ID NOS: 3-5, ora binding portion thereof. Such V_(I), chains can have framework regionssequences set forth as any of SEQ ID NOS: 6-38.

Provided herein is an antibody, or antigen-binding fragment thereof,comprising a light chain variable region having an amino acid sequenceset forth as SEQ ID NO: 3 and a heavy chain variable region having anamino acid sequence set forth as SEQ ID NO: 41.

Provided herein is an antibody, or antigen-binding fragment thereof,comprising a light chain variable region having an amino acid sequenceset forth as SEQ ID NO: 3 and a heavy chain variable region having anamino acid sequence set forth as SEQ ID NO: 41, wherein: the heavy chainvariable region further comprises one or more modifications selectedfrom the group consisting of a substitution of glycine (G) by alanine(A) at position 49; a substitution of asparagine (N) by serine (S) atposition 76; a substitution of threonine (T) by arginine (R) at position77; a substitution of leucine (L) by valine (V) at position 78; asubstitution of asparagine (N) by isoleucine (I) at position 82a; asubstitution of valine (V) by isoleucine (I) or leucine (L) at position89; a substitution of threonine (T) by arginine (R) or glycine (G) atposition 94; a substitution of leucine (L) by threonine (T) at position108; a substitution of valine (V) by leucine (L) at position 109; and asubstitution of serine (S) by alanine (A) at position 113 utilizing theKabat numbering system; and the light chain variable region furthercomprises one or more modifications selected from the group consistingof a substitution of aspartic acid (D) by glutamine (Q) at position 1; asubstitution of glutamine (Q) by valine (V) at position 3; asubstitution of methionine (M) by leucine (L) at position 4; asubstitution of threonine (T) by serine (S) at position 5; asubstitution of tyrosine (Y) by phenylalanine (F) at position 36; asubstitution of leucine (L) by proline (P) at position 46; asubstitution of leucine (L) by tryptophan (W) at position 47; asubstitution of serine (S) by valine (V) or alanine (A) at position 60;a substitution of aspartic acid (D) by serine (S) at position 70; asubstitution of phenylalanine (F) by tyrosine (Y) at position 71; asubstitution of glutamine (G) by alanine (A) at position 100; and asubstitution of isoleucine (I) by leucine (L) at position 106 utilizingthe Kabat numbering system.

Provided herein is an antibody, or antigen-binding fragment thereof,that binds endoglin comprising a heavy chain variable region having anamino acid sequence set forth as SEQ ID NO: 41, 42, or 43; and a lightchain variable region having an amino acid sequence set forth as SEQ IDNO: 3, 4, or 5. An antibody, or antigen-binding fragment thereof, cancomprise a heavy chain variable region having an amino acid sequence setforth as SEQ ID NO: 41 and a light chain variable region having an aminoacid sequence set forth as SEQ ID NO: 3. An antibody, or antigen-bindingfragment thereof, can comprise a heavy chain variable region having anamino acid sequence set forth as SEQ ID NO: 41 and a light chainvariable region having an amino acid sequence set forth as SEQ ID NO: 4.An antibody, or antigen-binding fragment thereof, can comprise a heavychain variable region having an amino acid sequence set forth as SEQ IDNO: 41 and a light chain variable region having an amino acid sequenceset forth as SEQ ID NO: 5. An antibody, or antigen-binding fragmentthereof, can comprise a heavy chain variable region having an amino acidsequence set forth as SEQ ID NO: 42 and a light chain variable regionhaving an amino acid sequence set forth as SEQ ID NO: 3. An antibody, orantigen-binding fragment thereof, can comprise a heavy chain variableregion having an amino acid sequence set forth as SEQ ID NO: 42 and alight chain variable region having an amino acid sequence set forth asSEQ ID NO: 4. An antibody, or antigen-binding fragment thereof, cancomprise a heavy chain variable region having an amino acid sequence setforth as SEQ ID NO: 42 and a light chain variable region having an aminoacid sequence set forth as SEQ ID NO: 5. An antibody, or antigen-bindingfragment thereof, can comprise a heavy chain variable region having anamino acid sequence set forth as SEQ ID NO: 43 and a light chainvariable region having an amino acid sequence set forth as SEQ ID NO: 3.An antibody, or antigen-binding fragment thereof, can comprise a heavychain variable region having an amino acid sequence set forth as SEQ IDNO: 43 and a light chain variable region having an amino acid sequenceset forth as SEQ ID NO: 4. An antibody, or antigen-binding fragmentthereof, can comprise a heavy chain variable region having an amino acidsequence set forth as SEQ ID NO: 43 and a light chain variable regionhaving an amino acid sequence set forth as SEQ ID NO: 5. Such antibodiescan bind to endoglin and inhibit angiogenesis.

In any of such embodiments, a heavy chain variable region can furthercomprise one or more modifications selected from the group consistingof: a substitution of asparagine (N) by serine (S) at position 76; asubstitution of threonine (T) by arginine (R) at position 77; asubstitution of asparagine (N) by isoleucine (I) at position 82a; asubstitution of valine (V) by isoleucine (I) or leucine (L) at position89; a substitution of threonine (T) by glycine (G) at position 94; asubstitution of leucine (L) by threonine (T) at position 108; asubstitution of valine (V) by leucine (L) at position 109; and asubstitution of serine (S) by alanine (A) a position 113; and the lightchain variable region can further comprise one or more modificationsselected from the group consisting of: a substitution of aspartic acid(D) by glutamine (Q) at position 1; a substitution of glutamine (Q) byvaline (V) at position 3; a substitution of threonine (T) by serine (S)at position 5; a substitution of tyrosine (Y) by phenylalanine (F) aposition 36; a substitution of serine (S) by valine (V) or alanine (A)at position 60; a substitution of aspartic acid (D) by serine (S) atposition 70; a substitution of glycine (G) by alanine (A) at position100, and a substitution of isoleucine (I) by leucine (L) at position 106utilizing the Kabat numbering system.

Provided herein is an antibody, or antigen-binding fragment thereof,that binds endoglin, comprising a heavy chain variable region and alight chain variable region, wherein said heavy chain variable regioncomprises:

-   -   (i) a CDR1 of SEQ ID NO: 66, a CDR2 of SEQ ID NO: 67, and a CDR3        of SEQ ID NO: 68;    -   (ii) a heavy chain FR1 having the amino acid sequence of SEQ ID        NO: 44 or the amino acid sequence of SEQ ID NO: 44 except for        one or more conservative substitutions;    -   (iii) a heavy chain FR2 having the amino acid sequence of SEQ ID        NO: 45 or the amino acid sequence of SEQ ID NO: 45 except for a        substitution of glycine (G) by alanine (A) at position 49        utilizing the Kabat numbering system; and    -   (iv) a heavy chain FR3 having the amino acid sequence of SEQ ID        NO: 47 or the amino acid sequence of SEQ ID NO: 47 except for        one or more substitutions selected from the group consisting of:        -   (a) a substitution of asparagine (N) by serine (S) at            position 76;        -   (b) a substitution of threonine (T) by arginine (R) at            position 77;        -   (c) a substitution of leucine (L) by valine (V) at position            78;        -   (d) a substitution of asparagine (N) by isoleucine (I) at            position 82a;        -   (e) a substitution of valine (V) by isoleucine (I) or            leucine (L) at position 89; and        -   (f) a substitution of threonine (T) by arginine (R) or            glycine (G) at position 94 utilizing the Kabat numbering            system; and    -   (v) a heavy chain FR4 having the amino acid sequence of SEQ ID        NO: 56 or the amino acid sequence of SEQ ID NO: 56 except for        one or more substitutions selected from the group consisting of:        -   (a) a substitution of leucine (L) by threonine (T) at            position 108;        -   (b) a substitution of valine (V) by leucine (L) at position            109; and        -   (c) a substitution of serine (S) by alanine (A) at position            113 utilizing the Kabat numbering system;    -   and said light chain variable region comprises:    -   (i) a CDR1 of SEQ ID NO: 63, a CDR2 of SEQ ID NO: 64, and a CDR3        of SEQ ID NO: 65;    -   (ii) a light chain FR1 having the amino acid sequence of SEQ ID        NO: 6 or the amino acid sequence of SEQ ID NO: 6 except for one        or more substitutions selected from the group consisting of:        -   (a) a substitution of aspartic acid (D) by glutamine (Q) at            position 1;        -   (b) a substitution of glutamine (Q) by valine (V) at            position 3;        -   (c) a substitution of methionine (M) by leucine (L) at            position 4; and        -   (d) a substitution of threonine (T) by serine (S) at            position 5; utilizing the Kabat numbering system; and    -   (iii) a light chain FR2 having the amino acid sequence of SEQ ID        NO: 20 or the amino acid sequence of SEQ ID NO: 20 except for        one or more substitutions selected from the group consisting of:        -   (a) a substitution of tyrosine (Y) by phenylalanine (F) at            position 36;        -   (b) a substitution of leucine (L) by proline (P) at position            46; and        -   (c) a substitution of leucine (L) by tryptophan (W) at            position 47 utilizing the Kabat numbering system; and    -   (iv) a light chain FR3 having the amino acid sequence of SEQ ID        NO: 28 or the amino acid sequence of SEQ ID NO: 28 except for        one or more substitutions selected from the group consisting of:        -   (a) a substitution of serine (S) by valine (V) or            alanine (A) at position 60;        -   (b) a substitution of aspartic acid (D) by serine (S) at            position 70; and        -   (b) a substitution of phenylalanine (F) by tyrosine (Y) at            position 71 utilizing the Kabat numbering system; and    -   (v) a light chain FR4 having the amino acid sequence of SEQ ID        NO: 35 or the amino acid sequence of SEQ ID NO: 35 except for        one or more substitutions selected from the group consisting of:        -   (a) a substitution of glycine (G) by alanine (A) at position            100; and        -   (b) a substitution of isoleucine (I) by leucine (L) at            position 106 utilizing the Kabat numbering system.

An antibody, or antigen-binding fragment thereof, provided herein cancomprise a heavy chain variable region CDR1 having an amino acidsequence as set forth in SEQ ID NO: 66, a heavy chain variable regionCDR2 having an amino acid sequence as set forth in SEQ ID NO: 67, aheavy chain variable region CDR3 having an amino acid sequence as setforth in SEQ ID NO: 68, a light chain variable region CDR1 having anamino acid sequence as set forth in SEQ ID NO: 63, a light chainvariable region CDR2 having an amino acid sequence as set forth in SEQID NO: 64, and a light chain variable region CDR3 having an amino acidsequence as set forth in SEQ ID NO: 65.

In one embodiment, the antibody, or antigen-binding fragment thereofbinds endoglin and comprises a heavy chain variable region FR1 having anamino acid sequence as set forth in SEQ ID NO: 44; a heavy chainvariable region FR2 having an amino acid sequence as set forth in SEQ IDNO: 45; a heavy chain variable region FR3 having an amino acid sequenceas set forth in SEQ ID NO: 47; a heavy chain variable region FR4 havingan amino acid sequence as set forth in SEQ ID NO: 56.

In another embodiment, the antibody, or antigen-binding fragment thereofbinds endoglin and comprises a heavy chain variable region FR1 having anamino acid sequence as set forth in SEQ ID NO: 44; a heavy chainvariable region FR2 having an amino acid sequence as set forth in SEQ IDNO: 46; a heavy chain variable region FR3 having an amino acid sequenceas set forth in SEQ ID NO: 48; a heavy chain variable region FR4 havingan amino acid sequence as set forth in SEQ ID NO: 56.

In another embodiment, the antibody, or antigen-binding fragmentthereof, comprises a light chain variable region FR1 having an aminoacid sequence as set forth in SEQ ID NO: 6; a light chain variableregion FR2 having an amino acid sequence as set forth in SEQ ID NO: 20;a light chain variable region FR3 having an amino acid sequence as setforth in SEQ ID NO: 28; and a light chain variable region FR4 having anamino acid sequence as set forth in SEQ ID NO: 35.

In another embodiment, the antibody, or antigen-binding fragment thereofbinds endoglin and comprises a light chain variable region FR1 having anamino acid sequence as set forth in SEQ ID NO: 6; a light chain variableregion FR2 having an amino acid sequence as set forth in SEQ ID NO: 21;a light chain variable region FR3 having an amino acid sequence as setforth in SEQ ID NO: 29; and a light chain variable region FR4 having anamino acid sequence as set forth in SEQ ID NO: 35.

In another embodiment, the antibody, or antigen-binding fragment thereofbinds endoglin and comprises a light chain variable region FR1 having anamino acid sequence as set forth in SEQ ID NO: 7; a light chain variableregion FR2 having an amino acid sequence as set forth in SEQ ID NO: 21;a light chain variable region FR3 having an amino acid sequence as setforth in SEQ ID NO: 29; and a light chain variable region FR4 having anamino acid sequence as set forth in SEQ ID NO: 35.

Provided herein is an antibody, or antigen-binding fragment thereof,comprising a heavy chain variable region having an amino acid sequenceset forth as SEQ ID NO: 42 and a light chain variable region having anamino acid sequence set forth as SEQ ID NO: 4.

Provided herein is an antibody, or antigen-binding fragment thereof,that binds endoglin, comprising a light chain variable region having anamino acid sequence set forth as SEQ ID NO: 4 and a heavy chain variableregion having an amino acid sequence set forth as SEQ ID NO: 42,wherein: said heavy chain variable region further comprises one or moremodifications selected from the group consisting of a substitution ofglycine (G) by alanine (A) at position 49; a substitution of asparagine(N) by serine (S) at position 76; a substitution of threonine (T) byarginine (R) at position 77; a substitution of leucine (L) by valine (V)at position 78; a substitution of asparagine (N) by isoleucine (I) atposition 82a; a substitution of valine (V) by isoleucine (I) or leucine(L) at position 89; a substitution of arginine (R) by threonine (T) orglycine (G) at position 94; a substitution of leucine (L) by threonine(T) at position 108; a substitution of valine (V) by leucine (L) atposition 109; and a substitution of serine (S) by alanine (A) atposition 113 utilizing the Kabat numbering system; and the light chainvariable region further comprises one or more modifications selectedfrom the group consisting of a substitution of aspartic acid (D) byglutamine (Q) at position 1; a substitution of glutamine (Q) by valine(V) at position 3; a substitution of methionine (M) by leucine (L) atposition 4; a substitution of threonine (T) by serine (S) at position 5;a substitution of tyrosine (Y) by phenylalanine (F) at position 36; asubstitution of proline (P) by leucine (L) at position 46; asubstitution of tryptophan (W) by leucine (L) at position 47; asubstitution of serine (S) by valine (V) or alanine (A) at position 60;a substitution of aspartic acid (D) by serine (S) at position 70; asubstitution of tyrosine (Y) by phenylalanine (F) at position 71; asubstitution of glutamine (G) by alanine (A) at position 100; and asubstitution of isoleucine (I) by leucine (L) at position 106 utilizingthe Kabat numbering system

Provided herein is an antibody, or antigen-binding fragment thereof,that binds endoglin, comprising a heavy chain variable region and alight chain variable region, wherein said heavy chain variable regioncomprises:

-   -   (i) a CDR 1 of SEQ ID NO: 66, a CDR2 of SEQ ID NO: 67, and a        CDR3 of SEQ ID NO: 68;    -   (ii) a heavy chain FR1 having the amino acid sequence of SEQ ID        NO: 44 or the amino acid sequence of SEQ ID NO 44 except for one        or more conservative substitutions;    -   (iii) a heavy chain FR2 having the amino acid sequence of SEQ ID        NO: 45 or the amino acid sequence of SEQ ID NO: 45 except for a        substitution of glycine (G) by alanine (A) at position 49        utilizing the Kabat numbering system; and    -   (iv) a heavy chain FR3 having the amino acid sequence of SEQ ID        NO: 47 or the amino acid sequence of SEQ ID NO: 47 except for        one or more substitutions selected from the group consisting of:        -   (a) a substitution of asparagine (N) by serine (S) at            position 76;        -   (b) a substitution of threonine (T) by arginine (R) at            position 77;        -   (c) a substitution of leucine (L) by valine (V) at position            78;        -   (d) a substitution of asparagine (N) by isoleucine (I) at            position 82a;        -   (e) a substitution of valine (V) by isoleucine (I) or            leucine (L) at position 89; and        -   (f) a substitution of arginine (R) by threonine (T) or            glycine (G) at position 94 utilizing the Kabat numbering            system; and    -   (v) a heavy chain FR4 having the amino acid sequence of SEQ ID        NO: 56 or the amino acid sequence of SEQ ID NO: 56 except for        one or more substitutions selected from the group consisting of:        -   (a) a substitution of leucine (L) by threonine (T) at            position 108;        -   (b) a substitution of valine (V) by leucine (L) at position            109; and        -   (c) a substitution of serine (S) by alanine (A) at position            113 utilizing the Kabat numbering system;    -   and said light chain variable region comprises:    -   (i) a CDR1 of SEQ ID NO: 63, a CDR2 of SEQ ID NO: 64, and a CDR3        of SEQ ID NO: 65;    -   (ii) a light chain FR1 having the amino acid sequence of SEQ ID        NO: 6 or the amino acid sequence of SEQ ID NO: 6 except for one        or more substitutions selected from the group consisting of:        -   (a) a substitution of aspartic acid (D) by glutamine (Q) at            position 1;        -   (b) a substitution of glutamine (Q) by valine (V) at            position 3;        -   (c) a substitution of methionine (M) by leucine (L) at            position 4; and        -   (d) a substitution of threonine (T) by serine (S) at            position 5; utilizing the Kabat numbering system; and    -   (iii) a light chain FR2 having the amino acid sequence of SEQ ID        NO: 21 or the amino acid sequence of SEQ ID NO: 20 except for        one or more substitutions selected from the group consisting of:        -   (a) a substitution of tyrosine (Y) by phenylalanine (F) at            position 36;        -   (b) a substitution of proline (P) by leucine (L) at position            46; and        -   (c) a substitution of tryptophan (W) by leucine (L) at            position 47 utilizing the Kabat numbering system; and    -   (iv) a light chain FR3 having the amino acid sequence of SEQ ID        NO: 29 or the amino acid sequence of SEQ ID NO: 28 except for        one or more substitutions selected from the group consisting of:        -   (a) a substitution of serine (S) by valine (V) or            alanine (A) at position 60;        -   (b) a substitution of aspartic acid (D) by serine (S) at            position 70; and        -   (b) a substitution of tyrosine (Y) by phenylalanine (F) at            position 71 utilizing the Kabat numbering system; and    -   (v) a light chain FR4 having the amino acid sequence of SEQ ID        NO: 35 or the amino acid sequence of SEQ ID NO: 35 except for        one or more substitutions selected from the group consisting of:        -   (a) a substitution of glycine (G) by alanine (A) at position            100; and        -   (b) a substitution of isoleucine (I) by leucine (L) at            position 106 utilizing the Kabat numbering system.

A substantial portion of a variable domain will include three CDRregions, together with their intervening framework regions. The portioncan also include at least about 50% of either or both of the first andfourth framework regions, the 50% being the C-terminal 50% of the firstframework region and the N-terminal 50% of the fourth framework region.Additional residues at the N-terminal or C-terminal end of thesubstantial part of the variable domain may be those not normallyassociated with naturally occurring variable domain regions. Forexample, construction of humanized endoglin antibodies andantigen-binding fragments described herein made by recombinant DNAtechniques can result in the introduction of N- or C-terminal residuesencoded by linkers introduced to facilitate cloning or othermanipulation steps. Other manipulation steps include the introduction oflinkers to join variable domains to further protein sequences includingimmunoglobulin heavy chains, other variable domains (for example in theproduction of diabodies) or protein labels as discussed in more detailbelow.

Humanized endoglin CDR3 regions having amino acid sequencessubstantially as set out as the CDR3 regions of the antibodies describedherein will be carried in a structure which allows for binding of theCDR3 regions to endoglin. The structure for carrying the CDR3s can be ofan antibody heavy or light chain sequence or substantial portion thereofin which the CDR3 regions are located at locations corresponding to theCDR3 region of naturally-occurring V_(H) and V_(L) antibody variabledomains encoded by rearranged immunoglobulin genes.

In one non-limiting example, provided herein are antibodies or antigenbinding fragments thereof containing a variable heavy chain having aCDR3 which has an amino acid sequence set forth as SEQ ID NO: 68 and/ora variable light chain having a CDR3 which has an amino acid sequenceset forth as SEQ ID NO: 65. In one embodiment, the variable heavy chainhas an amino acid sequence set forth as SEQ ID NO: 40 except for asubstitution of the CDR3 by the CDR3 amino sequence set forth as SEQ IDNO: 68. In another embodiment, the variable light chain has an aminoacid sequence set forth as SEQ ID NO: 2 except for a substitution of theCDR3 by the CDR3 amino acid sequence set forth as SEQ ID NO: 65.Additionally, such CDR3 containing variable regions/chains can compriseone or more FR amino acid sequences set forth as, for example, describedabove (or such FRs containing one or more additional modifications),where the antibodies or antigen binding fragments have 3 CDRs and 4 FRsin each of the VH and VL regions, have specific binding activity forendoglin and which are able to inhibit angiogenesis. Additionally,various antibody J segments can also be substituted within thesevariable regions for further variation within the variable regionchains.

In one aspect, variable heavy and light chains described herein can alsobe created by further replacing FR4 sequences. In one embodiment, heavychain FR4 sequences can be substituted for one of the following:

SEQ ID NO: Kabat-Number 103 104 105 106 107 108 109 110 111 112 113 76FRM4 from JH1, W G Q G T L V T V S S JH4 or JH5 77 FRM4 from JH2 W G R GT L V T V S S 78 FRM4 from JH3 W G Q G T M V T V S S 79 FRM4 from JH6 WG Q G T T V T V S S

In one embodiment, light chain FR4 sequences can be substituted for oneof the following:

SEQ ID NO Kabat Number 98 99 100 101 102 103 104 105 106 107 80 JK1 F GQ G T K V E I K 81 JK2 F G Q G T K L E I K 82 JK3 F G P G T K V D I K 83JK4 F G G G T K V E I K 84 JK5 F G Q G T R L E I K

Further provided herein are humanized versions of anti-endoglinantibodies alternatively named “superhumanized” anti-endoglin antibodiesor antigen-binding fragments thereof. Such superhumanized antibodies, orantigen-binding fragments thereof, can comprise a light chain variableregion having an amino acid sequence set forth as SEQ ID NOS: 71 or 72and a heavy chain variable region having an amino acid sequence setforth as SEQ ID NO: 75.

In another aspect, the present application provides a humanized antibodycapable of competing with a humanized anti-endoglin antibody orantigen-binding described herein under conditions in which at least 5%of an antibody having the V_(H) and V_(L) sequences of the antibody isblocked from binding to endoglin by competition with such an antibody inan ELISA assay.

Provided herein are neutralizing antibodies or antigen-binding fragmentsthat bind to endoglin and modulate the activity of endoglin. Theneutralizing antibody can for example, inhibit angiogenesis by bindingto endoglin.

Percentage of (%) inhibition of angiogenesis by an humanizedanti-endoglin antibody or antigen-binding fragment thereof of at least2-fold, at least 3-fold, at least 4-fold, at least 5-fold, at least6-fold, at least 7-fold, at least 8-fold, at least 9-fold, at least10-fold, at least 20-fold, at least 30-fold, at least 40-fold, at least50-fold, at least 60-fold, or greater than negative controls isindicative of a antibody or antigen-binding fragment thereof inhibitsangiogenesis. Percentage (%) of inhibition of angiogenesis by ahumanized anti-endoglin antibody or antigen-binding fragment thereof ofless than 2-fold greater than negative controls is indicative of anantibody or antigen-binding fragment thereof that does not inhibitangiogenesis.

Binding of an antibody or antigen-binding fragment to endoglin canpartially (e.g., 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%,98%, 99% or any number therein) or completely inhibit angiogenesis. Theneutralizing or inhibiting activity of an antibody or antigen-bindingfragment can be determined using an in vitro assay and/or in vivo usingart-recognized assays such as those described herein or otherwise knownin the art.

In one aspect, the antigen-binding fragment of any one of the humanizedantibodies described above is a Fab, a Fab′, a Fd, a F(ab′)₂, a Fv, ascFv, a single chain binding polypeptide (e.g., a scFv with Fc portion)or any other functional fragment thereof as described herein.

Antibodies or antigen-binding fragments described herein are useful indetection or diagnostic applications as described in more detail below.Antibodies or antigen-binding fragments described herein are useful forbinding to endoglin, which, in turn, can inhibit angiogenesis asdescribed herein.

Antibodies, or antigen-binding fragments thereof, described herein canbe further modified to alter the specific properties of the antibodywhile retaining the desired functionality, if needed. For example, inone embodiment, the compound can be modified to alter a pharmacokineticproperty of the compound, such as in vivo stability, solubility,bioavailability or half-life. Antibodies, or antigen-binding fragmentsthereof, described herein can further comprise a therapeutic moiety, adetectable moiety, or both, for use in diagnostic and/or therapeuticapplications.

Antibodies, or antigen-binding fragments thereof, described herein canalso be used as immunoconjugates. As used herein, for purposes of thespecification and claims, immunoconjugates refer to conjugates comprisedof the humanized anti-endoglin antibodies or fragments thereof accordingto the present invention and at least one therapeutic label. Therapeuticlabels include antitumor agents and angiogenesis-inhibitors. Suchantitumor agents are known in the art and include, but not limited to,toxins, drugs, enzymes, cytokines, radionuclides, photodynamic agents,and angiogenesis inhibitors. Toxins include, but are not limited to,ricin A chain, mutant Pseudomonas exotoxins, diphtheria toxoid,streptonigrin, boamycin, saporin, gelonin, and pokeweed antiviralprotein. Drugs include daunorubicin, methotrexate, and calicheamicins.Radionuclides include radiometals. Cytokines include, but are notlimited to, transforming growth factor (TGF)-β, interleukins,interferons, and tumor necrosis factors. Photodynamic agents include,but are not limited to, porphyrins and their derivatives. Additionaltherapeutic labels will be known in the art and are also contemplatedherein. The methods for complexing the anti-endoglin mAbs or a fragmentthereof with at least one antitumor agent are well known to thoseskilled in the art (i.e., antibody conjugates as reviewed by Ghetie etal., 1994, Pharmacol. Ther. 63:209-34). Such methods may utilize one ofseveral available heterobifunctional reagents used for coupling orlinking molecules. Additional radionuclides are further described hereinalong with additional methods for linking molecules, such as therapeuticand diagnostic labels.

Antibodies, or antigen-binding fragments thereof, can be modified usingtechniques known in the art for various purposes such as, for example,by addition of polyethylene glycol (PEG). PEG modification (PEGylation)can lead to one or more of improved circulation time, improvedsolubility, improved resistance to proteolysis, reduced antigenicity andimmunogenicity, improved bioavailability, reduced toxicity, improvedstability, and easier formulation (for a review see, Francis et al.,International Journal of Hematology 68:1-18, 1998).

In the case of an antigen-binding fragment which does not contain an Fcportion, an Fc portion can be added to (e.g., recombinantly) thefragment, for example, to increase half-life of the antigen-bindingfragment in circulation in blood when administered to a patient. Choiceof an appropriate Fc region and methods of to incorporate such fragmentsare known in the art. Incorporating a Fc region of an IgG into apolypeptide of interest so as to increase its circulatory half-life, butso as not to lose its biological activity can be accomplished usingconventional techniques known in the art such as, for example, describedin U.S. Pat. No. 6,096,871, which is hereby incorporated by reference inits entirety. Fc portions of antibodies can be further modified toincrease half-life of the antigen-binding fragment in circulation inblood when administered to a patient. Modifications can be determinedusing conventional means in the art such as, for example, described inU.S. Pat. No. 7,217,798, which is hereby incorporated by reference inits entirety.

Other methods of improving the half-life of antibody-based fusionproteins in circulation are also known such as, for example, describedin U.S. Pat. Nos. 7,091,321 and 6,737,056, each of which is herebyincorporated by reference. Additionally, antibodies and antigen-bindingfragments thereof may be produced or expressed so that they do notcontain fucose on their complex N-glycoside-linked sugar chains. Theremoval of the fucose from the complex N-glycoside-linked sugar chainsis known to increase effector functions of the antibodies andantigen-binding fragments, including but not limited to, antibodydependent cell-mediated cytotoxicity (ADCC) and complement dependentcytotoxicity (CDC). Similarly, antibodies or antigen-binding fragmentsthereof that can bind endoglin can be attached at their C-terminal endto all or part of an immunoglobulin heavy chain derived from anyantibody isotype, e.g., IgG, IgA, IgE, IgD and IgM and any of theisotype sub-classes, particularly IgG1, IgG2b, IgG2a, IgG3 and IgG4.

Additionally, the antibodies or antigen-binding fragments describedherein can also be modified so that they are able to cross theblood-brain barrier. Such modification of the antibodies orantigen-binding fragments described herein allows for the treatment ofbrain diseases such as glioblastoma multiforme (GBM). Exemplarymodifications to allow proteins such as antibodies or antigen-bindingfragments to cross the blood-brain barrier are described in US PatentApplication Publication 2007/0082380 which is hereby incorporated byreference in its entirety.

Glycosylation of immunoglobulins has been shown to have significanteffects on their effector functions, structural stability, and rate ofsecretion from antibody-producing cells (Leatherbarrow et al., Mol.Immunol. 22:407 (1985)). The carbohydrate groups responsible for theseproperties are generally attached to the constant (C) regions of theantibodies. For example, glycosylation of IgG at asparagine 297 in theC_(H) 2 domain is required for full capacity of IgG to activate theclassical pathway of complement-dependent cytolysis (Tao and Morrison,J. Immunol. 143:2595 (1989)). Glycosylation of IgM at asparagine 402 inthe C_(H) 3 domain is necessary for proper assembly and cytolyticactivity of the antibody (Muraoka and Shulman, J. Immunol. 142:695(1989)). Removal of glycosylation sites as positions 162 and 419 in theC_(H) 1 and C_(H)3 domains of an IgA antibody led to intracellulardegradation and at least 90% inhibition of secretion (Taylor and Wall,Mol. Cell. Biol. 8:4197 (1988)). Additionally, antibodies andantigen-binding fragments thereof may be produced or expressed so thatthey do not contain fucose on their complex N-glycoside-linked sugarchains. The removal of the fucose from the complex N-glycoside-linkedsugar chains is known to increase effector functions of the antibodiesand antigen-binding fragments, including but not limited to, antibodydependent cell-mediated cytotoxicity (ADCC) and complement dependentcytotoxicity (CDC). These “defucosylated” antibodies and antigen-bindingfragments may be produced through a variety of systems utilizingmolecular cloning techniques known in the art, including but not limitedto, transgenic animals, transgenic plants, or cell-lines that have beengenetically engineered so that they no longer contain the enzymes andbiochemical pathways necessary for the inclusion of a fucose in thecomplex N-glycoside-linked sugar chains (also known asfucosyltransferase knock-out animals, plants, or cells). Non-limitingexamples of cells that can be engineered to be fucosyltransferaseknock-out cells include CHO cells, SP2/0 cells, NS0 cells, and YB2/0cells.

Glycosylation of immunoglobulins in the variable (V) region has alsobeen observed. Sox and Hood reported that about 20% of human antibodiesare glycosylated in the V region (Proc. Natl. Acad. Sci. USA 66:975(1970)). Glycosylation of the V domain is believed to arise fromfortuitous occurrences of the N-linked glycosylation signalAsn-Xaa-Ser/Thr in the V region sequence and has not been recognized inthe art as playing a role in immunoglobulin function.

Glycosylation at a variable domain framework residue can alter thebinding interaction of the antibody with antigen. The present inventionincludes criteria by which a limited number of amino acids in theframework or CDRs of a humanized immunoglobulin chain are chosen to bemutated (e.g., by substitution, deletion, or addition of residues) inorder to increase the affinity of an antibody.

Affinity for binding a pre-determined polypeptide antigen can,generally, be modulated by introducing one or more mutations into the Vregion framework, typically in areas adjacent to one or more CDRs and/orin one or more framework regions. Typically, such mutations involve theintroduction of conservative amino acid substitutions that eitherdestroy or create the glycosylation site sequences but do notsubstantially affect the hydropathic structural properties of thepolypeptide. Typically, mutations that introduce a proline residue areavoided. Glycosylation of antibodies and antigen-binding fragmentsthereof is further described in U.S. Pat. No. 6,350,861, which isincorporated by reference herein with respect to glycosylation.

Antibodies, or antigen-binding fragments thereof, can be formulated forshort-term delivery or extended (long term) delivery.

Antibodies, or antigen-binding fragments thereof, that bind to endoglincan also be used for purification of endoglin and/or to detect endoglinlevels in a sample or patient to detect or diagnose a disease ordisorder associated with endoglin as described in more detail below.

Humanized antibodies; antigen-binding fragments, and binding proteinswhich bind endoglin generated using such methods can be tested for oneor more of their binding affinity, avidity, and neutralizingcapabilities. Useful humanized antibodies, antigen-binding fragments,and binding proteins can be used to administer a patient to prevent,inhibit, manage or treat a condition disease or disorder associated withangiogenesis.

Provided herein are methods of identifying humanized antibodies orantigen-binding fragments thereof that bind to endoglin. Antibodies andantigen-binding fragments can be evaluated for one or more of bindingaffinity, association rates, disassociation rates and avidity. In oneaspect, antibodies can be evaluated for their ability to neutralize theactivity of endoglin or a polypeptide in which the endoglin bindingsequence is present. Measurement binding affinity, association rates,disassociation rates and avidity can be accomplished usingart-recognized assays including (Surface Plasmon Resonance), but notlimited to, an enzyme-linked-immunosorbent assay (ELISA), ScatchardAnalysis, BIACORE analysis, etc., as well as other assays commonly usedand known to those of ordinary skill in the art.

Measurement of binding of antibodies to endoglin and/or the ability ofthe antibodies and antigen-binding fragments thereof, for example, toinhibit angiogenesis, can be determined using, for example, anenzyme-linked-immunosorbent assay (ELISA), a competitive binding assay,an ELISPOT assay, or any other useful assay known in the art. Theseassays are commonly used and well-known to those of ordinary skill inthe art.

In one non-limiting embodiment, an ELISA assay can be used to measurethe binding capability of specific antibodies or antigen-bindingfragments that bind to endoglin.

Assays, such as an ELISA, also can be used to identify antibodies orantigen-binding fragments thereof which exhibit increased specificityfor endoglin in comparison to other antibodies or antigen-bindingfragments thereof. Assays, such as an ELISA, also can be used toidentify antibodies or antigen-binding fragments thereof with bind toepitopes across one or more polypeptides and across one or more speciesof endoglin. The specificity assay can be conducted by running parallelELISAs in which a test antibodies or antigen-binding fragments thereofis screened concurrently in separate assay chambers for the ability tobind one or more epitopes on different species of the polypeptidecontaining the endoglin epitopes to identify antibodies orantigen-binding fragments thereof that bind to endoglin. Anothertechnique for measuring apparent binding affinity familiar to those ofskill in the art is a surface plasmon resonance technique (analyzed on aBIACORE 2000 system) (Liljeblad, et al., Glyco. J. 2000, 17:323-329).Standard measurements and traditional binding assays are described byHeeley, R. P., Endocr. Res. 2002, 28:217-229.

Humanized antibodies to endoglin can also be assayed for their abilityto treat various diseases and conditions associated with angiogenesis,e.g., various forms of ocular diseases characterized byangiogenesis/neovascularization (e.g., macular degeneration, diabeticretinopathy), diabetic nephropathy, chronic inflammatory diseases (e.g.,IBD), rheumatoid arthritis, osteoarthritis, and various forms of cancer(primary tumors and metastases). Any suitable assay known to one ofskill in the art can be used to monitor such effects. Several suchtechniques are described herein. In one example, the antibodies andantigen-binding fragments described herein are assayed for their abilityto bind endoglin. In another example, affinity constants for theantibodies and antigen-binding fragments described herein are determinedby surface plasmon resonance (SPR). In yet another example, theantibodies and antigen-binding fragments described herein are assayedfor their effect on the inhibition of angiogenesis.

II. Compositions

Each of the compounds described herein can be used as a composition whencombined with an acceptable carrier or excipient. Such compositions areuseful for in vitro or in vivo analysis or for administration to asubject in vivo or ex vivo for treating a subject with the disclosedcompounds.

Thus pharmaceutical compositions can include, in addition to activeingredient, a pharmaceutically acceptable excipient, carrier, buffer,stabilizer or other materials well known to those skilled in the art.Such materials should be non-toxic and should not interfere with theefficacy of the active ingredient. The precise nature of the carrier orother material will depend on the route of administration.

Pharmaceutical formulations comprising a protein of interest, e.g., anantibody or antigen-binding fragment, identified by the methodsdescribed herein can be prepared for storage by mixing the proteinhaving the desired degree of purity with optional physiologicallyacceptable carriers, excipients or stabilizers (Remington'sPharmaceutical Sciences 16th edition, Osol, A. Ed. (1980)), in the formof lyophilized formulations or aqueous solutions. Acceptable carriers,excipients, or stabilizers are those that are non-toxic to recipients atthe dosages and concentrations employed, and include buffers such asphosphate, citrate, and other organic acids; antioxidants includingascorbic acid and methionine; preservatives (such asoctadecyldimethylbenzyl ammonium chloride; hexamethonium chloride;benzalkonium chloride, benzethonium chloride; phenol, butyl or benzylalcohol; alkyl parabens such as methyl or propyl paraben; catechol;resorcinol; cyclohexanol; 3-pentanol; and m-cresol); low molecularweight (less than about 10 residues) polypeptides; proteins, such asserum albumin, gelatin, or immunoglobulins; hydrophilic polymers such aspolyvinylpyrrolidone; amino acids such as glycine, glutamine,asparagine, histidine, arginine, or lysine; monosaccharides,disaccharides, and other carbohydrates including glucose, mannose, ordextrins; chelating agents such as EDTA; sugars such as sucrose,mannitol, trehalose or sorbitol; salt-forming counter-ions such assodium; metal complexes (e.g., Zn-protein complexes); and/or non-ionicsurfactants such as TWEEN®, PLURONICS® or polyethylene glycol (PEG).

Acceptable carriers are physiologically acceptable to the administeredpatient and retain the therapeutic properties of the compounds with/inwhich it is administered. Acceptable carriers and their formulations areand generally described in, for example, Remington' pharmaceuticalSciences (18th Edition, ed. A. Gennaro, Mack Publishing Co., Easton, Pa.1990). One exemplary carrier is physiological saline. The phrase“pharmaceutically acceptable carrier” as used herein means apharmaceutically acceptable material, composition or vehicle, such as aliquid or solid filler, diluent, excipient, solvent or encapsulatingmaterial, involved in carrying or transporting the subject compoundsfrom the administration site of one organ, or portion of the body, toanother organ, or portion of the body, or in an in vitro assay system.Each carrier is acceptable in the sense of being compatible with theother ingredients of the formulation and not injurious to a subject towhom it is administered. Nor should an acceptable carrier alter thespecific activity of the subject compounds.

In one aspect, provided herein are pharmaceutically acceptable orphysiologically acceptable compositions including solvents (aqueous ornon-aqueous), solutions, emulsions, dispersion media, coatings, isotonicand absorption promoting or delaying agents, compatible withpharmaceutical administration. Pharmaceutical compositions orpharmaceutical formulations therefore refer to a composition suitablefor pharmaceutical use in a subject. The pharmaceutical compositions andformulations include an amount of a compound described herein and apharmaceutically or physiologically acceptable carrier.

Compositions can be formulated to be compatible with a particular routeof administration (i.e., systemic or local). Thus, compositions includecarriers, diluents, or excipients suitable for administration by variousroutes.

In another embodiment, the compositions can further comprise, if needed,an acceptable additive in order to improve the stability of thecompounds in composition and/or to control the release rate of thecomposition. Acceptable additives do not alter the specific activity ofthe subject compounds. Exemplary acceptable additives include, but arenot limited to, a sugar such as mannitol, sorbitol, glucose, xylitol,trehalose, sorbose, sucrose, galactose, dextran, dextrose, fructose,lactose and mixtures thereof. Acceptable additives can be combined withacceptable carriers and/or excipients such as dextrose. Alternatively,exemplary acceptable additives include, but are not limited to, asurfactant such as polysorbate 20 or polysorbate 80 to increasestability of the peptide and decrease gelling of the solution. Thesurfactant can be added to the composition in an amount of 0.01% to 5%of the solution. Addition of such acceptable additives increases thestability and half-life of the composition in storage.

The pharmaceutical composition can be administered, for example, byinjection, including, but not limited to, subcutaneous, subcutaneous,intravitreal, intradermal, intravenous, intra-arterial, intraperitoneal,or intramuscular injection. Excipients and carriers for use informulation of compositions for each type of injection are contemplatedherein. The following descriptions are by example only and are not meantto limit the scope of the compositions. Compositions for injectioninclude aqueous solutions (where water soluble) or dispersions andsterile powders for the extemporaneous preparation of sterile injectablesolutions or dispersion. For intravenous administration, suitablecarriers include physiological saline, bacteriostatic water, CremophorEL™ (BASF, Parsippany, N.J.) or phosphate buffered saline (PBS). Thecarrier can be a solvent or dispersion medium containing, for example,water, ethanol, polyol (for example, glycerol, propylene glycol, andliquid polyetheylene glycol, and the like), and suitable mixturesthereof. Fluidity can be maintained, for example, by the use of acoating such as lecithin, by the maintenance of the required particlesize in the case of dispersion and by the use of surfactants.Antibacterial and antifungal agents include, for example, parabens,chlorobutanol, phenol, ascorbic acid and thimerosal. Isotonic agents,for example, sugars, polyalcohols such as manitol, sorbitol, and sodiumchloride may be included in the composition. The resulting solutions canbe packaged for use as is, or lyophilized; the lyophilized preparationcan later be combined with a sterile solution prior to administration.For intravenous, injection, or injection at the site of affliction, theactive ingredient will be in the form of a parenterally acceptableaqueous solution which is pyrogen-free and has suitable pH, isotonicityand stability. Those of relevant skill in the art are well able toprepare suitable solutions using, for example, isotonic vehicles such asSodium Chloride Injection, Ringer's Injection, Lactated Ringer'sInjection. Preservatives, stabilizers, buffers, antioxidants and/orother additives may be included, as needed. Sterile injectable solutionscan be prepared by incorporating an active ingredient in the requiredamount in an appropriate solvent with one or a combination ofingredients enumerated above, as required, followed by filteredsterilization. Generally, dispersions are prepared by incorporating theactive ingredient into a sterile vehicle which contains a basicdispersion medium and the required other ingredients from thoseenumerated above. In the case of sterile powders for the preparation ofsterile injectable solutions, the preferred methods of preparation arevacuum drying and freeze drying which yields a powder of the activeingredient plus any additional desired ingredient from a previouslysterile-filtered solution thereof.

Compositions can be conventionally administered intravitreally,sub-cutaneous, or via intravitreal implant.

Compositions can be conventionally administered intravenously, such asby injection of a unit dose, for example. For injection, an activeingredient can be in the form of a parenterally acceptable aqueoussolution which is substantially pyrogen-free and has suitable pH,isotonicity and stability. One can prepare suitable solutions using, forexample, isotonic vehicles such as Sodium Chloride Injection, Ringer'sInjection, Lactated Ringer's Injection. Preservatives, stabilizers,buffers, antioxidants and/or other additives may be included, asrequired. Additionally, compositions can be administered viaaerosolization. (Lahn et al., Aerosolized Anti-T-cell-ReceptorAntibodies Are Effective against Airway Inflammation andHyperreactivity, Int. Arch. Allegery Immuno., 134: 49-55 (2004)).

In one embodiment, the composition is lyophilized, for example, toincrease shelf-life in storage. When the compositions are considered foruse in medicaments or any of the methods provided herein, it iscontemplated that the composition can be substantially free of pyrogenssuch that the composition will not cause an inflammatory reaction or anunsafe allergic reaction when administered to a human patient. Testingcompositions for pyrogens and preparing compositions substantially freeof pyrogens are well understood to one or ordinary skill of the art andcan be accomplished using commercially available kits.

Acceptable carriers can contain a compound that stabilizes, increases ordelays absorption or clearance. Such compounds include, for example,carbohydrates, such as glucose, sucrose, or dextrans; low molecularweight proteins; compositions that reduce the clearance or hydrolysis ofpeptides; or excipients or other stabilizers and/or buffers. Agents thatdelay absorption include, for example, aluminum monostearate andgelatin. Detergents can also be used to stabilize or to increase ordecrease the absorption of the pharmaceutical composition, includingliposomal carriers. To protect from digestion the compound can becomplexed with a composition to render it resistant to acidic andenzymatic hydrolysis, or the compound can be complexed in anappropriately resistant carrier such as a liposome. Means of protectingcompounds from digestion are known in the art (see, e.g., Fix (1996)Pharm Res. 13:1760 1764; Samanen (1996) J. Pharm. Pharmacol. 48:119 135;and U.S. Pat. No. 5,391,377, describing lipid compositions for oraldelivery of therapeutic agents).

The phrase “pharmaceutically acceptable” refers to molecular entitiesand compositions that are physiologically tolerable and do not typicallyproduce an allergic or similar untoward reaction, such as gastric upset,dizziness and the like, when administered to a human.

The term “unit dose” when used in reference to a therapeutic compositionrefers to physically discrete units suitable as unitary dosage forhumans, each unit containing a predetermined quantity of active materialcalculated to produce the desired therapeutic effect in association withthe required diluent; i.e., carrier, or vehicle.

The compositions can be administered in a manner compatible with thedosage formulation, and in a therapeutically effective amount. Thequantity to be administered depends on the subject to be treated,capacity of the subject's immune system to utilize the activeingredient, and degree of binding capacity desired. Precise amounts ofactive ingredient required to be administered depend on the judgment ofthe practitioner and are peculiar to each individual. Suitable regimesfor initial administration and booster shots are also variable, but aretypified by an initial administration followed by repeated doses at oneor more hour intervals by a subsequent injection or otheradministration. Alternatively, continuous intravenous infusionsufficient to maintain concentrations in the blood are contemplated.

One embodiment contemplates the use of the compositions described hereinto make a medicament for treating a condition, disease or disorderdescribed herein. Medicaments can be formulated based on the physicalcharacteristics of the patient/subject needing treatment, and can beformulated in single or multiple formulations based on the stage of thecondition, disease or disorder. Medicaments can be packaged in asuitable package with appropriate labels for the distribution tohospitals and clinics wherein the label is for the indication oftreating a subject having a disease described herein. Medicaments can bepackaged as a single or multiple units. Instructions for the dosage andadministration of the compositions can be included with the packages asdescribed below. The invention is further directed to medicaments of ahumanized anti-endoglin antibody or antigen binding fragment thereofdescribed hereinabove and a pharmaceutically acceptable carrier.

Provided herein are compositions of humanized antibodies andantigen-binding fragments thereof that bind endoglin and include thosesuch as described elsewhere herein. Humanized antibodies andantigen-binding fragments thereof that bind endoglin as described hereincan be used for the treatment of various forms of ocular diseasescharacterized by angiogenesis/neovascularization (e.g., maculardegeneration, diabetic retinopathy), diabetic nephropathy, chronicinflammatory diseases (e.g., IBD), rheumatoid arthritis, osteoarthritis,and various forms of cancer (primary tumors and metastases).

A composition (an antibody or an antigen-binding fragment describedherein) can be administered alone or in combination with a secondcomposition either simultaneously or sequentially dependent upon thecondition to be treated. In one embodiment, a second therapeutictreatment is an angiogenesis inhibitor (as described herein). When twoor more compositions are administered, the compositions can beadministered in combination (either sequentially or simultaneously). Acomposition can be administered in a single dose or multiple doses.

In one embodiment of the present invention, the compositions areformulated to be free of pyrogens such that they are acceptable foradministration to human patients. Testing compositions for pyrogens andpreparing pharmaceutical compositions free of pyrogens are wellunderstood to one of ordinary skill in the art.

One embodiment of the present invention contemplates the use of any ofthe compositions of the present invention to make a medicament fortreating a disorder of the present invention. Medicaments can beformulated based on the physical characteristics of the patient/subjectneeding treatment, and can be formulated in single or multipleformulations based on the disorder. Medicaments of the present inventioncan be packaged in a suitable pharmaceutical package with appropriatelabels for the distribution to hospitals and clinics wherein the labelis for the indication of treating a disorder as described herein in asubject. Medicaments can be packaged as a single or multiple units.Instructions for the dosage and administration of the pharmaceuticalcompositions of the present invention can be included with thepharmaceutical packages.

III. Methods of Use

Provided herein is a method of inducing a response in a patient (humanor non-human) by administering to the patient a composition of anantibody or antigen-binding fragment thereof that preferentially bindsto endoglin. The binding site to which the antibody binds can be acontinuous or conformation/dis-continuous epitope.

An effective response of the present invention is achieved when thepatient experiences partial or total alleviation or reduction of signsor symptoms of illness, and specifically includes, without limitation,prolongation of survival and/or visual acuity. The expectedprogression-free survival times may be measured in months to years,depending on prognostic factors including the number of relapses, stageof disease, and other factors. Prolonging survival includes withoutlimitation times of at least 1 month (mo), about at least 2 mos., aboutat least 3 mos., about at least 4 mos., about at least 6 mos., about atleast 1 year, about at least 2 years, about at least 3 years, etc.Overall survival can be also measured in months to years. Alternatively,an effective response may be that a patient's symptoms remain static.Further indications of treatment of indications are described in moredetail below.

Compositions of antibodies and antigen-binding fragments describedherein can be used as non-therapeutic agents (e.g., as affinitypurification agents). Generally, in one such embodiment, a protein ofinterest is immobilized on a solid phase such a Sephadex resin or filterpaper, using conventional methods known in the art. The immobilizedprotein is contacted with a sample containing the target of interest (orfragment thereof) to be purified, and thereafter the support is washedwith a suitable solvent that will remove substantially all the materialin the sample except the target protein, which is bound to theimmobilized antibody. Finally, the support is washed with anothersuitable solvent, such as glycine buffer, pH 5.0, which will release thetarget protein. In addition to purification, compositions can be usedfor detection, diagnosis and therapy of diseases and disordersassociated with endoglin and angiogenesis.

The term “contacting” as used herein refers to adding together asolution or composition of a compound with a liquid medium bathing thepolypeptides, cells, tissue or organ from an organism. Alternately,“contacting” refers to mixing together a solution or composition of acompound, with a liquid such as blood, serum, or plasma derived from anorganism. For in vitro applications, a composition can also compriseanother component, such as dimethyl sulfoxide (DMSO). DMSO facilitatesthe uptake of the compounds or solubility of the compounds. The solutioncomprising the test compound may be added to the medium bathing thecells, tissues, or organs, or mixed with another liquid such as blood,by utilizing a delivery apparatus, such as a pipette-based device orsyringe-based device. For in vivo applications, contacting can occur,for example, via administration of a composition to a patient by anysuitable means; compositions with pharmaceutically acceptable excipientsand carriers have been described in more detail above.

A “patient” (e.g., a mammal such as a human or a non-human animal suchas a primate, rodent, cow, horse, pig, sheep, etc.) according to oneembodiment of the present application, is a mammal who exhibits one ormore clinical manifestations and/or symptoms of a disease or disorderdescribed herein. In certain situations, the patient may be asymptomaticand yet still have clinical manifestations of the disease or disorder.An antibody or antigen-binding fragment thereof can be conjugated to atherapeutic moiety or be a fusion protein containing a therapeuticmoiety. An antibody or antigen-binding fragment thereof can beconjugated to a detectable moiety or be a fusion protein containing adetectable moiety. In one embodiment, the antibody or antigen-bindingfragment thereof can be conjugated to both a therapeutic moiety and adetectable moiety. An antibody or antigen-binding fragment thereof canbe conjugated to, or recombinantly engineered with, an affinity tag(e.g., a purification tag). Affinity tags such as, for example, His6tags (SEQ ID NO: 85) are conventional in the art.

Antibodies or antigen-binding fragments thereof provided herein are suchthat they can be conjugated or linked to a therapeutic moiety and/or animaging or a detectable moiety and/or an affinity tag. Methods forconjugating or linking polypeptides are well known in the art.Associations (binding) between compounds and labels include any meansknown in the art including, but not limited to, covalent andnon-covalent interactions, chemical conjugation as well as recombinanttechniques.

A. Binding of Endoglin and Angiogenesis

Endoglin (CD105) is expressed on the cell surface as a 180 kDahomodimeric transmembrane protein. The external domain binds TGF-β1 and−3 isoforms with high affinity (50 nM), and the transmembrane and theintracellular domains of CD105 share a 71% sequence similarity withbetaglycan. The human CD105 gene is located on chromosome 9q34,identified using fluorescence in situ hybridization, and the codingregion contains 14 exons, and two different isoforms (L and S) of CD105with capacity to bind TGF-β have been characterized. The L-CD105consists of 633 amino acid residues with 47 amino acid residues in thecytoplasmic tail as opposed to the S-CD105, which consists of 600 aminoacid residues with a 14 amino acid cytoplasmic tail. However, L-CD105 isthe predominant form. CD105 is constitutively phosphorylated inendothelial cells, mainly on serine and threonine residues, and thisphosphorylation is due to the constitutively active TGF-β RII within thecell. TGF-β binding to CD105 results in down-regulation ofphosphorylation, similar to effects seen with protein kinase Cinhibitors. The human CD105 amino acid sequence contains the tripeptidearginine-glycine-aspartic acid (RGD) located in an exposed region of theextracellular domain. The RGD peptide is a key recognition structurefound on ECM proteins such as fibronectin, vitronectin, von Willebrandfactor (vWF), type I collagen, and fibrinogen and is recognized by cellsurface integrins. Integrin adhesion has been implicated in hemostasis,thrombosis, angiogenesis and inflammation, processes in which theendothelium plays a critical role. (Duff et al., FASEB J., 17:984-992(2003)).

CD105 is a member of the TGF-β receptor family that is expressed byproliferating endothelial cells. Normal levels of CD105 are needed forendothelial cell proliferation. CD105 expression is increased bycellular hypoxia through the production of hypoxia-inducible factor-1-α(HIF-1-α) and protects hypoxic cells from apoptosis. Several functionsof CD105 are associated with TGF-β signaling. TGF-β signals throughheterodimeric receptors consisting of serine kinases, receptor I (RI),and receptor II (RII). Binding of TGF-β to the external domains of thereceptor unmasks the cytoplasmic RII kinase activity that phosphorylatesthe TGF-β RI, which can then interact with downstream signalers such asthe Smad proteins. CD105 forms part of the TGF-β receptor complex but itcan exist independently on the cell surface. In many cells in vitro,CD105 suppresses TGF-β signaling.

CD105 also binds other growth factors such as activin A and bonemorphogenic proteins (BMP) −10, −9, −7 and −2. Binding of TGF-β or othergrowth factor ligands to CD105 requires the presence of at least thereceptor RII, and it cannot bind ligands by itself. CD105 associationwith receptors does not alter their affinity for the ligand itself. Uponassociation, the cytoplasmic domain of CD105 is phosphorylated by TGF-βRI and TGF-β RII; then TGF-β RI, but not TGF-β RII, kinase dissociatesfrom the receptor complex.

CD105 expression inhibits phosphorylation levels of TGF-β RII butincreases that of TGF-β RI, resulting in increased phosphorylation ofSmad 2 but not Smad 3. Since Smad 2 can interact with a variety oftranscription factors, co-activators, and suppressors, phosphorylatedSmad 2 may act as an integrator of multiple signals to modulate genetranscription. Thus, CD105 modulates TGF-β functions via interactionwith TGF-β RI and TGF-β RII and modifies the phosphorylation ofdownstream Smad proteins.

CD105 acts to modulate signaling of multiple kinase receptor complexesof the TGF-β superfamily, including TGF-β receptors (TGF-βR), activinreceptor-like kinases (ALK) and activin receptors. In the absence ofCD105, activation of TGF-β receptors results in phosphorylation of SMADproteins (SMAD 2 and 3) that inhibit endothelial cell growth. However,activation of CD105 by TGF-β modulates SMAD protein phosphorylation(including the phosphorylation of SMAD 1, 5 and 8). The end result isrelease of the growth inhibitory effects of TGF-β receptor activation onendothelial cells (see FIG. 3). Not surprisingly, prevention of CD105activation by anti-CD105 antibody or antisense oligonucleotide actssynergistically with TGF-β to suppress endothelial cell growth.

The CD105 promoter is 2.6 kb in length but does not contain TATA or CAATtranscription initiation boxes. However, it has two GC-rich regions,consensus motifs for Sp1, ets, GATA, AP-2, NGF-β, and Mad, as well asTGF-β response elements. Nonetheless, CD105 has a relatively restrictedcellular distribution. The basal level of transcription appears torequire an ets site at position −68 and the Sp1 sites, but the relativerestriction of expression, for example, to endothelial cells, appears toinvolve multiple regulatory regions, in particular, one at −1294 to −932and another very close to the transcription initiation site. CD105 isup-regulated by TGF-β, and this has been shown to require a Sp1 site at−37 to −29, also involving one or more juxtaposed upstream SBE sitesbinding Smads 3 and/or 4 (which are activated by TGF-β signaling).Hypoxia is a common feature of ischemic tissues and tumors, and is apotent stimulator for CD105 gene expression in vascular endothelialcells (ECs). Such an effect is potentiated in combination with TGF-β 1.The up-regulated CD105 can exert a self-protective role in ECs underhypoxic stress.

Vascular EC are the major source of CD105. Other cell types includingvascular smooth muscle cells, fibroblasts, macrophages, leukemic cellsof pre-B and myelomonocytic origin, and erythroid precursors expressCD105 to a lesser extent.

CD105 is involved in angiogenesis. Antisense experiments havedemonstrated that suppression of CD105 expression in HUVEC results inmarked inhibition of in vitro angiogenesis in combination with TGF-β1,indicating that CD105 is a proangiogenic component in the endothelialcells. Further evidence of the important role of CD105 in angiogenesiscomes from CD105 knockout mice. The CD105 null mice exhibit multiplevascular and cardiac defects leading to heath at an early embryonicstage. Severe vascular impairments observed in CD105 null mice indicatethat CD105 is required for the formation of mature blood vessels in theextraembryonic vasculature, further confirming the direct role ofendoglin in angiogenesis.

Endoglin, also known as, inter alia, CD105 or edg-1, is a type Ihomodimeric membrane glycoprotein which is expressed at high levels inproliferating vascular endothelial cells. Thus, endoglin is primarily aproliferation-associated marker for endothelial cells undergoing activeangiogenesis. However, there may be limited expression of endoglin bythe vascular endothelium of normal tissues. Human endoglin is known tospecifically bind transforming growth factor-β (TGF-β), and the deducedamino acid sequence of endoglin has strong homology to β-glycan, a typeof TGF-β receptor.

Endoglin (EDG) has been targeted in antibody-based methods of reducingtumor vasculature, as EDG is a proliferation-associated antigen onendothelial and leukemia cells. Its expression is up-regulated intumor-associated vascular endothelium, and EDG is essential forangiogenesis. Angiogenesis includes the formation of new capillary bloodvessels leading to neovascularization as well as the maintenance of theexisting vasculature. It is a complex process which includes a series ofsequential steps including endothelial cell-mediated degradation ofvascular basement membrane and interstitial matrices, migration ofendothelial cells, proliferation of endothelial cells, and formation ofcapillary loops by endothelial cells.

Provided herein are humanized antibodies that bind endoglin. Endoglincan be found on cells that comprise and support existing vasculature aswell as cells that are promoting the growth of, and become part of, newvasculature. The antibodies can bind endoglin and thereby inhibitangiogenesis, inhibit the existing vasculature or the maintenance of theexisting vasculature, and/or inhibit small vessel dilation. In additionto their use for purification of endoglin, these antibodies are usefulfor purification, detection and diagnostic purposes as well astherapeutic purposes. The antibodies provided herein can be used for theformulation of medicaments for the treatment a variety of conditions anddiseases, methods to treat said conditions and diseases and methods ofdetection or diagnosis.

Murine monoclonal antibodies (mAbs) have been raised against endoglinwhich modulate endoglin activity and thereby inhibit angiogenesis and/orinhibit vasodilation of small blood vessels. These murine antibodies aredescribed in U.S. Pat. Nos. 5,928,641, 6,200,566, 6,190,660, and7,097,836, each of which is hereby incorporated in their entirety.Additionally, the ex vivo and in vivo efficiency of a number of theseantibodies has been demonstrated; monoclonal antibodies that bindendoglin are of interest as endoglin modulating compounds. Therapeuticuse of murine antibodies is not feasible, however, as administration ofthe murine antibodies has a number of limitations, includingimmunogenicity in, for example, the form of human anti-mouse antibodies(HAMA).

“Angiogenesis” is used herein to include all aspects of blood vesselmaintenance and development. Thus, angiogenesis includes the formationof new capillary blood vessels leading to neovascularization as well asthe maintenance and control of the existing vasculature and small bloodvessels. Angiogenesis is a complex process which includes a series ofsequential steps including endothelial cell-mediated degradation ofvascular basement membrane and interstitial matrices, migration ofendothelial cells, proliferation of endothelial cells, and formation ofcapillary loops by endothelial cells. Angiogenesis is inclusive of thegrowth and/or development of new blood vessels (also referred to asneovascularization), dilation of the small vessels, excessive orprolonged vascular growth, and maintenance of the existing vasculature.Endoglin is known to be involved in the regulation of angiogenesis andis believed to be involved in multiple biochemical pathways related tothe induction of angiogenesis. (Duff et al., FASEB J., 17:984-992(2003); Bernabeu et al., J. Cell. Biochem., 102(6):1375-1388 (2007)).

As used herein, the terms “angiogenesis inhibitory,” “angiogenesisinhibiting” or “anti-angiogenic” include inhibition of vasculogenesis,and are intended to mean affecting a decrease in the extent, amount, orrate of neovascularization. Effecting a decrease in the extent, amount,or rate of endothelial cell proliferation or migration in the tissue isa specific example of inhibiting angiogenesis.

The term “angiogenesis inhibitory composition” refers to a compositionwhich inhibits angiogenesis-mediated processes such as endothelial cellmigration, proliferation, tube formation and subsequently leading to theinhibition of the generation of new blood vessels from existing ones,and consequently affects angiogenesis-dependent conditions.

The term “angiogenesis-associated disease” is used herein, for purposesof the specification and claims, to mean certain pathological processesin humans where angiogenesis is abnormally prolonged. This furtherincludes angiogenesis conditions and diseases, such as those diseasesand conditions related to, caused by, or associated with angiogenesis.Non-limiting examples of such diseases include various forms of oculardiseases characterized by angiogenesis/neovascularization (e.g., maculardegeneration, diabetic retinopathy), diabetic nephropathy, chronicinflammatory diseases (e.g., IBD), rheumatoid arthritis, osteoarthritis,and various forms of cancers and metastasis. The antibodies andantigen-binding fragments thereof described herein can be used to treatan angiogenesis-associated disease by binding endoglin and inhibitingangiogenesis.

The term “anti-angiogenic therapy” is used herein, for purposes of thespecification and claims, to mean therapy targeted to cells and/orvasculature expressing endoglin (expressed at higher levels onproliferating vasculature as compared to quiescent vasculature); thisfurther includes therapy that is directed against angiogenesis (i.e.,the formation of new capillary blood vessels leading toneovascularization), therapy that is directed against existingvasculature and/or excessive vascularization or blood vessel growth,therapy directed towards the dilation of small vessels, and therapydirected to a disease or condition (e.g., vascular targeting therapy).Exemplary diseases or conditions contemplated within the inventioninclude, but are not limited to, various forms of ocular diseasescharacterized by angiogenesis/neovascularization (e.g., maculardegeneration, diabetic retinopathy), diabetic nephropathy, chronicinflammatory diseases (e.g., IBD), rheumatoid arthritis, osteoarthritis,and various forms of cancer, solid tumors, and metastases.

“Ocular disease characterized by neovascularization” is used herein, forpurposes of the specification and claims, to mean any ocular diseasecaused by, or resulting in, increased angiogenesis within any portion ofthe eye, including the retina, cornea, pupil, iris, vitreous humor oraqueous humor. Such diseases include for example, age-related maculardegeneration, diabetic retinopathy, non-diabetic retinopathy, choroidalneovascularization (CNV) and sub-retinal neovascularization (SRN orSRNV) and neoplasms of the eye.

B. Diagnostic Applications

Humanized anti-endoglin antibodies and fragments thereof can be used forin vivo and in vitro detection, diagnostic and/or monitoring purposes.Endoglin is believed to be involved in multiple diseases and disordersas described further below. Treatment of endoglin related diseases andconditions depends, in part, upon their diagnosis, and the antibodiesand antigen-binding fragments thereof described herein are useful forthe diagnosis of excess endoglin or for diagnosis for diseases andconditions associated with endoglin activity.

Provided herein is method of detecting levels of endoglin in a sample ora subject comprising (i) contacting an antibody or antigen bindingfragment described herein with the sample or subject, and (ii) detectinga complex of the antibody or antigen-binding fragment thereof andendoglin.

Provided herein is a method of imaging or diagnosing angiogenesis or anangiogenic-dependent disease or disorder, comprising contacting acomposition of an antibody or antigen-binding fragment thereof asdescribed herein with a sample. The sample can be, for example, blood,serum, plasma, platelets, biopsy fluid, spinal tap fluid, meninges andurine. Imaging or diagnosis method can occur in an in vitro assay.Alternatively, when contacting is by administration of the compositionto a patient, the angiogenesis or angiogenic-dependent disease ordisorder is imaged or diagnosed in vivo.

In one embodiment, the antibody or antigen-binding fragment furthercomprises a detectable moiety. Detection can occur in vitro, in vivo orex vivo. In vitro assays for the detection and/or determination(quantification, qualification, etc.) of endoglin with the antibodies orantigen-binding fragments thereof include but are not limited to, forexample, ELISAs, RIAs and western blots. In vitro detection, diagnosisor monitoring of endoglin can occur by obtaining a sample (e.g., a bloodsample) from a patient and testing the sample in, for example, astandard ELISA assay. For example, a 96-well microtiter plate can becoated with an antibody or antigen-binding fragment thereof describedherein, washed and coating with PBS-Tween/BSA to inhibit non-specificbinding. The blood sample can be serially diluted and placed induplicate wells compared to a serially-diluted standard curve ofendoglin. After incubating and washing the wells, an anti-endoglinantibody labeled with biotin can be added, followed by addition ofstreptavidin-alkaline phosphatase. The wells can be washed and asubstrate (horseradish peroxidase) added to develop the plate. The platecan be read using a conventional plate reader and software.

When detection occurs in vivo, contacting occurs via administration ofthe antibody or antigen binding fragment using any conventional meanssuch as those described elsewhere herein. In such methods, detection ofendoglin in a sample or a subject can be used to diagnose a disease ordisorder associated with, or correlated with the activity of endoglinsuch as those diseases and disorders described herein.

In the in vivo detection, diagnosis or monitoring of endoglin, a patientis administered an antibody or antigen-binding fragment that binds toendoglin, which antibody or antigen-binding fragment is bound to adetectable moiety. The detectable moiety can be visualized usingart-recognized methods such as, but not limited to, magnetic resonanceimaging (MRI), fluorescence, radioimaging, light sources supplied byendoscopes, laparoscopes, or intravascular catheter (i.e., via detectionof photoactive agents), photoscanning, positron emission tomography(PET) scanning, whole body nuclear magnetic resonance (NMR),radioscintography, single photon emission computed tomography (SPECT),targeted near infrared region (NIR) scanning, X-ray, ultrasound, etc.such as described, for example, in U.S. Pat. No. 6,096,289, U.S. Pat.No. 7,115,716, U.S. Pat. No. 7,112,412, U.S. Patent Application No.20030003048 and U.S. Patent Application No. 20060147379, each of whichis incorporated herein in its entirety by reference. Labels fordetecting compounds using such methods are also known in the art anddescribed in such patents and applications and are incorporated hereinby reference. Visualization of the detectable moiety can allow fordetection, diagnosis, and/or monitoring of a condition or diseaseassociated with endoglin and/or angiogenesis.

Additional diagnostic assays that utilize antibodies specific to thedesired target protein, i.e., endoglin, are known in the art and arealso contemplated herein.

Non-limiting conditions, diseases and disorders to be considered forthese methods include, but are not limited to, those associated withangiogenesis such as, for example, various forms of ocular diseasescharacterized by angiogenesis/neovascularization (e.g., maculardegeneration, diabetic retinopathy), diabetic nephropathy, chronicinflammatory diseases (e.g., IBD), rheumatoid arthritis, osteoarthritis,and various forms of cancer (primary tumors and metastases). In thedetection, diagnosis or monitoring of such diseases, the subject patientis administered a composition of an antibody or antigen-binding fragmentthereof described herein, which antibody or antigen-binding fragmentthereof is conjugated to a detectable moiety. The moiety can bevisualized using art-recognized methods such as those described above.Visualization of the detectable moiety can allow for detection,diagnosis, and/or monitoring of such conditions and diseases.

For in vitro detection methods, samples to be obtained from a patientinclude, but are not limited to, blood, tissue biopsy samples and fluidtherefrom.

Thus, the present invention provides humanized antibodies andantigen-binding fragments thereof against endoglin which are useful fordetecting or diagnosing levels of endoglin associated with a disease ordisorder, potentially indicating need for therapeutic treatment. Incertain embodiments, the antibodies comprise a humanized anti-endoglinantibody described herein. In other embodiments the antibody furthercomprises a second agent. Such an agent can be a molecule or moiety suchas, for example, a reporter molecule or a detectable label. Detectablelabels/moieties for such detection methods are known in the art and aredescribed in more detail below. Reporter molecules are any moiety whichcan be detected using an assay. Non-limiting examples of reportermolecules which have been conjugated to polypeptides include enzymes,radiolabels, haptens, fluorescent labels, phosphorescent molecules,chemiluminescent molecules, chromophores, luminescent molecules,photoaffinity molecules, colored particles or ligands, such as biotin.Detectable labels include compounds and/or elements that can be detecteddue to their specific functional properties, and/or chemicalcharacteristics, the use of which allows the polypeptide to which theyare attached to be detected, and/or further quantified if desired. Manyappropriate detectable (imaging) agents are known in the art, as aremethods for their attachment to polypeptides (see, for e.g., U.S. Pat.Nos. 5,021,236; 4,938,948; and 4,472,509, each of which is herebyincorporated by reference).

Methods of joining polypeptides such as antibodies with detectablemoieties are known in the art and include, for example, recombinant DNAtechnology to form fusion proteins and conjugation (e.g., chemicalconjugation). Methods for preparing fusion proteins by chemicalconjugation or recombinant engineering are well-known in the art.Methods of covalently and non-covalently linking components are alsoknown in the art. See, e.g., Williams (1995) Biochemistry 34:1787 1797;Dobeli (1998) Protein Expr. Purif. 12:404-414; and Kroll (1993) DNACell. Biol. 12: 441-453.

It may be necessary, in some instances, to introduce an unstructuredpolypeptide linker region between a label or a moiety and one or moreportion of the antibodies, antigen-binding fragments or binding proteinsdescribed herein. A linker can facilitate enhanced flexibility, and/orreduce steric hindrance between any two fragments. The linker can alsofacilitate the appropriate folding of each fragment to occur. The linkercan be of natural origin, such as a sequence determined to exist inrandom coil between two domains of a protein. One linker sequence is thelinker found between the C-terminal and N-terminal domains of the RNApolymerase a subunit. Other examples of naturally occurring linkersinclude linkers found in the ICI and LexA proteins.

Within a linker, an amino acid sequence can be varied based on thecharacteristics of the linker as determined empirically or as revealedby modeling. Considerations in choosing a linker include flexibility ofthe linker, charge of the linker, and presence of some amino acids ofthe linker in the naturally-occurring subunits. The linker can also bedesigned such that residues in the linker contact deoxyribose nucleicacid (DNA), thereby influencing binding affinity or specificity, or tointeract with other proteins. In some cases, such as when it isnecessary to span a longer distance between subunits or when the domainsmust be held in a particular configuration, the linker can, optionally,contain an additional folded domain. In some embodiments, the design ofa linker can involve an arrangement of domains which requires the linkerto span a relatively short distance, e.g., less than about 10 Angstroms(Å). However, in certain embodiments, linkers span a distance of up toabout 50 Angstroms.

Within the linker, the amino acid sequence can be varied based on thecharacteristics of the linker as determined empirically or as revealedby modeling. Considerations in choosing a linker include flexibility ofthe linker, charge of the linker, and presence of some amino acids ofthe linker in the naturally-occurring subunits. The linker can also bedesigned such that residues in the linker contact DNA, therebyinfluencing binding affinity or specificity, or to interact with otherproteins. In some cases, when it is necessary to span a longer distancebetween subunits or when the domains must be held in a particularconfiguration, the linker can optionally contain an additional foldeddomain.

Methods for coupling polypeptides (free or cell-bound) to beads areknown in the art. Methods for selecting coupled polypeptides or cellsdisplaying a polypeptide are also known in the art. Briefly,paramagnetic polystyrene microparticles are commercially available(Spherotech, Inc., Libertyville, Ill.; Invitrogen, Carlsbad, Calif.)that couple peptides to microparticle surfaces that have been modifiedwith functional groups or coated with various antibodies or ligands suchas, for example, avidin, streptavidin or biotin.

The paramagnetic property of microparticles allows them to be separatedfrom solution using a magnet. The microparticles can be easilyre-suspended when removed from the magnet. Polypeptides can be coupledto paramagnetic polystyrene microparticles coated with a polyurethanelayer in a tube. The hydroxy groups on the microparticle surface areactivated by reaction with p-toluensulphonyl chloride (Nilsson K andMosbach K. “p-Toluenesulfonyl chloride as an activating agent of agarosefor the preparation of immobilized affinity ligands and proteins.” Eur.J. Biochem. 1980:112: 397-402). Alternatively, paramagnetic polystyrenemicroparticles containing surface carboxylic acid can be activated witha carbodiimide followed by coupling to a polypeptide, resulting in astable amide bond between a primary amino group of the polypeptide andthe carboxylic acid groups on the surface of the microparticles(Nakajima N and Ikade Y, Mechanism of amide formation by carbodiimidefor bioconjugation in aqueous media, Bioconjugate Chem. 1995, 6(1):123-130; Gilles M A, Hudson A Q and Borders C L Jr, Stability ofwater-soluble carbodiimides in aqueous solution, Anal Biochem. 1990 Feb.1; 184(2):244-248; Sehgal D and Vijay I K, a method for the highefficiency of water-soluble carbodiimide-mediated amidation, AnalBiochem. 1994 April; 218(1):87-91; Szajani B et al, Effects ofcarbodiimide structure on the immobilization of enzymes, Appl BiochemBiotechnol. 1991 August; 30(2): 225-231). Another option is to couplebiotinylated polypeptides to paramagnetic polystyrene microparticleswhose surfaces have been covalently linked with a monolayer ofstreptavidin. (Argarana C E, Kuntz I D, Birken S, Axel R, Cantor C R.Molecular cloning and nucleotide sequence of the streptavidin gene.Nucleic Acids Res. 1986; 14(4):1871-82; Pahler A, Hendrickson W A,Gawinowicz Kolks M A, Aragana C E, Cantor C R. Characterization andcrystallization of core streptavidin. J Biol Chem1987:262(29):13933-13937).

Polypeptides can be conjugated to a wide variety of fluorescent dyes,quenchers and haptens such as fluorescein, R-phycoerythrin, and biotin.Conjugation can occur either during polypeptide synthesis or after thepolypeptide has been synthesized and purified. Biotin is a small (244kilodaltons) vitamin that binds with high affinity to avidin andstreptavidin proteins and can be conjugated to most peptides withoutaltering their biological activities. Biotin-labeled polypeptides areeasily purified from unlabeled polypeptides using immobilizedstreptavidin and avidin affinity gels, and streptavidin oravidin-conjugated probes can be used to detect biotinylated polypeptidesin, for example, ELISA, dot blot or Western blot applications.N-hydroxysuccinimide esters of biotin are the most commonly used type ofbiotinylation agent. N-hydroxysuccinimide-activated biotins reactefficiently with primary amino groups in physiological buffers to formstable amide bonds. Polypeptides have primary amines at the N-terminusand can also have several primary amines in the side chain of lysineresidues that are available as targets for labeling withN-hydroxysuccinimide-activated biotin reagents. Several differentN-hydroxysuccinimide esters of biotin are available, with varyingproperties and spacer arm length (Pierce, Rockford, Ill.). Thesulfo-N-hydroxysuccinimide ester reagents are water soluble, enablingreactions to be performed in the absence of organic solvents.

The mole-to-mole ratio of biotin to polypeptide can be estimated using a2-(4′-Hydroxyazobenzene-2-carboxylic acid) assay using art-recognizedtechniques (Green, N M, (1975) “Avidin. In Advances in ProteinChemistry.” Academic Press, New York. 29, 85-133; Green, N M, (1971)“The use of bifunctional biotinyl compounds to determine the arrangementof subunits in avidin.” Biochem J. 125, 781-791; Green, N M., (1965) “Aspectrophotometric assay for avidin and biotin based on binding of dyesby avidin.” Biochem. J. 94: 23c-24c). Several biotin molecules can beconjugated to a polypeptide and each biotin molecule can bind onemolecule of avidin. The biotin-avidin bond formation is very rapid andstable in organic solvents, extreme pH and denaturing reagents. Toquantitate biotinylation, a solution containing the biotinylatedpolypeptide is added to a mixture of2-(4′-Hydroxyazobenzene-2-carboxylic acid) and avidin. Because biotinhas a higher affinity for avidin, it displaces the2-(4′-Hydroxyazobenzene-2-carboxylic acid) and the absorbance at 500nanometers decreases proportionately. The amount of biotin in a solutioncan be quantitated in a single cuvette by measuring the absorbance ofthe 2-(4′-Hydroxyazobenzene-2-carboxylic acid)-avidin solution beforeand after addition of the biotin-containing peptide. The change inabsorbance relates to the amount of biotin in the sample by theextinction coefficient of the 2-(4′-Hydroxyazobenzene-2-carboxylicacid)-avidin complex.

Alternatively, an antibody, antigen-binding fragment or binding proteincan be conjugated with a fluorescent moiety Conjugating polypeptideswith fluorescent moieties (e.g., R-Phycoerythrin, fluoresceinisothiocyanate (FITC), etc.) can be accomplished using art-recognizedtechniques described in, for example, Glazer, A N and Stryer L. (1984).Trends Biochem. Sci. 9:423-7; Kronick, M N and Grossman, P D (1983)Clin. Chem. 29:1582-6; Lanier, L L and Loken, M R (1984) J. Immunol.,132:151-156; Parks, D R et al. (1984) Cytometry 5:159-68; Hardy, R R etal. (1983) Nature 306:270-2; Hardy R R et al. (1984) J. Exp. Med.159:1169-88; Kronick, M N (1986) J. Immuno. Meth. 92:1-13; Der-Balian G,Kameda, N. and Rowley, G. (1988) Anal. Biochem. 173:59-63.

In one non-limiting embodiment, an antibody antigen-binding fragment canbe associated with (conjugated to) a detectable label, such as aradionuclide, iron-related compound, a dye, an imaging agent or afluorescent agent for immunodetection of endoglin which can be used tovisualize binding of the antibodies to endoglin in vitro and/or in vivo.

Non-limiting examples of radiolabels include, for example, ³²P, ³³P,⁴³K, ⁵²Fe, ⁵⁷Co, ⁶⁴Cu, ⁶⁷Ga, ⁶⁷Cu, ⁶⁸Ga, ⁷¹Ge, ⁷⁵Br, ⁷⁶Br, ⁷⁷Br, ⁷⁷As,⁷⁷Br, ⁸¹Rb/⁸¹MKr, ⁸⁷MSr, ⁹⁰Y, ⁹⁷Ru, ⁹⁹Tc, ¹⁰⁰Pd, ¹⁰¹Rh, ¹⁰³Pb, ¹⁰⁵Rh,¹⁰⁹Pd, ¹¹¹Ag, ¹¹¹In, ¹¹³In, ¹¹⁹Sb, ¹²¹Sn, ¹²³I, ¹²⁵I, ¹²⁷Cs, ¹²⁸Ba,¹²⁹Cs, ¹³¹I, ¹³¹Cs, ¹⁴³Pr, ¹⁵³Sm, ¹⁶¹Tb, ¹⁶⁶Ho, ¹⁶⁹Eu, ¹⁷⁷Lu, ¹⁸⁶Re,¹⁸⁸Re, ¹⁸⁹Re, ¹⁹¹Os, ¹⁹³Pt, ¹⁹⁴Ir, ¹⁹⁷Hg, ¹⁹⁹Au, ²⁰³Pb, ²¹¹At, ²¹²Pb,²¹²Bi and ²¹³Bi. Radiolabels can be attached to compounds usingconventional chemistry known in the art of antibody imaging.Radiolabeled compounds are useful in in vitro diagnostics techniques andin in vivo radioimaging techniques and in radioimmunotherapy. Forexample, in the instance of in vivo imaging, the antibodies andantigen-binding fragments thereof can be conjugated to an imaging agentrather than a radioisotope(s), including but not limited to a magneticresonance image enhancing agent, wherein for instance an antibodymolecule is loaded with a large number of paramagnetic ions throughchelating groups. Examples of chelating groups include EDTA, porphyrins,polyamines crown ethers and polyoximes. Examples of paramagnetic ionsinclude gadolinium, iron, manganese, rhenium, europium, lanthanium,holmium and ferbium. Such detectable moieties also include: metals;metal chelators; lanthanides; lanthanide chelators; radiometals;radiometal chelators; positron-emitting nuclei; microbubbles (forultrasound); liposomes; molecules microencapsulated in liposomes ornanosphere; monocrystalline iron oxide nanocompounds; magnetic resonanceimaging contrast agents; light absorbing, reflecting and/or scatteringagents; colloidal particles; fluorophores, such as near-infraredfluorophores. In many embodiments, such secondary functionality/moietywill be relatively large, e.g., at least 25 amu in size, and in manyinstances can be at least 50, 100 or 250 amu in size. In certainembodiments, the secondary functionality is a chelate moiety forchelating a metal, e.g., a chelator for a radiometal or paramagneticion. In embodiments, it is a chelator for a radionuclide useful forradiotherapy or imaging procedures.

Antagonists of the invention also can be assayed for their ability tomodulate angiogenesis in a tissue. Any suitable assay known to one ofskill in the art can be used to monitor such effects. Several suchtechniques are described herein.

One measures angiogenesis is an in vivo rabbit eye model and is referredto as the rabbit eye assay. The rabbit eye assay has been described indetail by others, and further has been used to measure both angiogenesisand neovascularization in the presence of angiogenic inhibitors such asthalidomide. See D'Amato et al. (1994) Proc. Natl. Acad. Sci.91:4082-4085.

The rabbit eye assay is a well recognized assay model for in vivoangiogenesis because the neovascularization process, exemplified byrabbit blood vessels growing from the rim of the cornea into the cornea,is easily visualized through the naturally transparent cornea of theeye. Additionally, both the extent and the amount of stimulation orinhibition of neovascularization or regression of neovascularization caneasily be monitored over time.

Finally, the rabbit is exposed to any test reagent, and therefore thehealth of the rabbit is an indication of toxicity of the test reagent.

Another assay measures angiogenesis in the chimeric mouse:human mousemodel and is referred to as the chimeric mouse assay. The assay has beendescribed in detail by others, and further has been described herein tomeasure angiogenesis, neovascularization, and regression of tumortissues. See Yan, et al. (1993) J. Clin. Invest. 91:986-996.

The chimeric mouse assay is a useful assay model for in vivoangiogenesis because the transplanted skin grafts closely resemblenormal human skin histologically and neovascularization of whole tissueis occurring wherein actual human blood vessels are growing from thegrafted human skin into the human tumor tissue on the surface of thegrafted human skin. The origin of the neovascularization into the humangraft can be demonstrated by immunohistochemical staining of theneovasculature with human-specific endothelial cell markers.

The chimeric mouse assay demonstrates regression of neovascularizationbased on both the amount and extent of regression of new vessel growth.Furthermore, it is easy to monitor effects on the growth of any tissuetransplanted upon the grafted skin, such as a tumor tissue. Finally, theassay is useful because there is an internal control for toxicity in theassay system. The chimeric mouse is exposed to any test reagent, andtherefore the health of the mouse is an indication of toxicity. Otheranimal models described herein and known in the art can also be utilizedin the methods described herein.

C. Treatment with Humanized Endoglin Antibodies

Provided herein are methods of preventing or treating one or morediseases or disorders associated with angiogenesis/neovascularization,excessive vascularization, or small vessel dilation comprisingadministering a composition comprising a humanized antibody orantigen-binding fragment described herein that binds to endoglinassociated with the disease or disorder and prevents angiogenesis,thereby preventing, treating, ameliorating, or lessening the disease orits severity.

Provided herein are methods of preventing or treating one or morediseases or disorders associated with angiogenesis/neovascularizationcomprising administering a composition comprising a humanized antibodyor antigen-binding fragment described herein that binds to endoglinassociated with the disease or disorder, decreases angiogenesis, orprevents excessive angiogenesis.

As used herein, “prevention” refers to prophylaxis, prevention of onsetof symptoms, prevention of progression of a disease or disorderassociated with angiogenesis or correlated with endoglin activity. Asused herein, “inhibition,” “treatment” and “treating” are usedinterchangeably and refer to, for example, stasis of symptoms,prolongation of survival, partial or full amelioration of symptoms, andpartial or full eradication of a condition, disease or disorderassociated with angiogenesis or correlated with endoglin activity.

Compositions can be administered to a patient in a therapeuticallyeffective amount which are effective for producing some desiredtherapeutic effect by inhibiting a disease or disorder such as describedherein which can be associated with endoglin, at a reasonablebenefit/risk ratio applicable to any medical treatment. For theadministration of the present compositions to human patients, thecompositions can be formulated by methodology known by one of ordinaryskill in the art. A therapeutically effective amount is an amountachieves at least partially a desired therapeutic or prophylactic effectin an organ or tissue. The amount of a humanized anti-endoglin antibodyor antigen binding fragment thereof necessary to bring about preventionand/or therapeutic treatment of a disease or disorder is not fixed perse. The amount of humanized anti-endoglin antibody or antigen bindingfragment thereof administered may vary with the type of disease,extensiveness of the disease, and size of the mammal suffering from thedisease or disorder. In one embodiment, two or more humanizedanti-endoglin antibodies described herein are administered to a patientin combination. Combination includes concomitant or subsequentadministration of the antibodies.

“Administering” is defined herein as a means providing the compositionto the patient in a manner that results in the composition being insidethe patient's body. Such an administration can be by any routeincluding, without limitation, locally, regionally or systemically bysubcutaneous, intravitreal, intradermal, intravenous, intra-arterial,intraperitoneal, or intramuscular administration (e.g., injection).“Concurrent administration” means administration within a relativelyshort time period from each other; such time period can be less than 2weeks, less than 7 days, less than 1 day and could even be administeredsimultaneously.

Actual dosage levels of the active ingredients in the compositions canbe varied so as to obtain an amount of the active ingredient that iseffective to achieve the desired therapeutic response for a particularpatient, composition, and mode of administration, without being toxic tothe patient. The selected dosage level will depend upon a variety offactors including the activity of the particular compound employed, theroute of administration, the time of administration, the rate ofexcretion of the particular compound being employed, the duration of thetreatment, other drugs, compounds and/or materials used in combinationwith the particular composition employed, the age, sex, weight,condition, general health and prior medical history of the patient beingtreated, and like factors well known in the medical arts. The antibodiesand antigen-binding fragments described herein can be administered to asubject in various dosing amounts and over various time frames.Non-limiting doses include about 0.01 mg/kg, about 0.05 mg/kg, about 0.1mg/kg, about 0.5 mg/kg, about 1 mg/kg, about 5 mg/kg, about 10 mg/kg,about 20 mg/kg, about 30 mg/kg, about 40 mg/kg, about 50 mg/kg, about 60mg/kg, about 70 mg/kg, about 80 mg/kg, about 90 mg/kg, about 100 mg/kg,about 125 mg/kg, about 150 mg/kg, about 175 mg/kg, about 200 mg/kg, orany integer in between. Additionally, the dose(s) of an antibody orantigen-binding fragment can be administered twice a week, weekly, everytwo weeks, every three weeks, every 4 weeks, every 6 weeks, every 8weeks, every 12 weeks, or any combination of weeks therein. Dosingcycles are also contemplated such as, for example, administeringantibodies or antigen-binding fragments thereof one or twice a week for4 weeks, followed by two weeks without therapy. Additional dosing cyclesincluding, for example, different combinations of the doses and weeklycycles described herein are also contemplated within the invention.

“Contacting” is defined herein as a means of bringing a composition asprovided herein in physical proximity with a cell, organ, tissue orfluid as described herein. Contacting encompasses systemic or localadministration of any of the compositions provided herein and includes,without limitation, in vitro, in vivo and/or ex vivo procedures andmethods. “Combining” and “contacting” are used interchangeably hereinand are meant to be defined in the same way.

A response is achieved when the patient experiences partial or totalalleviation, or reduction of signs or symptoms of illness, andspecifically includes, without limitation, prolongation of survival. Theexpected progression-free survival times can be measured in months toyears, depending on prognostic factors including the number of relapses,stage of disease, and other factors. Prolonging survival includeswithout limitation times of at least 1 month (mo), about at least 2months (mos.), about at least 3 mos., about at least 4 mos., about atleast 6 mos., about at least 1 year, about at least 2 years, about atleast 3 years, or more. Overall survival can also be measured in monthsto years. The patient's symptoms can remain static or can decrease.

A physician or veterinarian having ordinary skill in the art can readilydetermine and prescribe the effective amount (ED50) of the compositionrequired. For example, the physician or veterinarian could start dosesof the compounds employed in the composition at levels lower than thatrequired in order to achieve the desired therapeutic effect andgradually increase the dosage until the desired effect is achieved.Alternatively, a dose can remain constant.

Compositions can be administered to a patient by any convenient routesuch as described above. Regardless of the route of administrationselected, the compounds of the present invention, which can be used in asuitable hydrated form, and/or the compositions, are formulated intoacceptable dosage forms such as described below or by other conventionalmethods known to those of skill in the art.

Antibodies can be combined with a therapeutic moiety or to a detectable(imaging) moiety using methods known in the art such as, for example,chemical conjugation, covalent or non-covalent bonds or recombinanttechniques to create conjugates or fusion proteins such as described inmore detail below. Alternatively, antibodies and/or other agents can becombined in separate compositions for simultaneous or sequentialadministration.

Toxicity and therapeutic efficacy of such ingredient can be determinedby standard pharmaceutical procedures in cell cultures or experimentalanimals, e.g., for determining the LD₅₀ (the dose lethal to 50% of thepopulation) and the ED₅₀ (the dose therapeutically effective in 50% ofthe population). The dose ratio between toxic and therapeutic effects isthe therapeutic index and it can be expressed as the ratio LD₅₀/ED₅₀.While compounds that exhibit toxic side effects may be used, care shouldbe taken to design a delivery system that targets such compounds to thesite of affected tissue in order to minimize potential damage to healthycells and, thereby, reduce side effects.

Data obtained from cell culture assays and animal studies can be used informulating a range of dosage for use in humans. The dosage of suchcompounds lies preferably within a range of circulating concentrationsthat include the ED₅₀ with little or no toxicity. The dosage may varywithin this range depending upon the dosage form employed and the routeof administration utilized. For any compound used in the method of theinvention, the therapeutically effective dose can be estimated initiallyfrom cell culture assays. A dose can be formulated in animal models toachieve a circulating plasma concentration arrange that includes theIC₅₀ (i.e., the concentration of the test compound which achieves ahalf-maximal inhibition) as determined in cell culture. Levels in plasmacan be measured, for example, by high performance liquid chromatography.Such information can be used to more accurately determine useful dosesin humans.

The pro-angiogenic role of endoglin has been established in many modelsincluding endothelial cell culture and knock-out mouse models.Endothelial and the associated cells are well known to express endoglin(CD105), and the role of endoglin in angiogenesis, generally, as well ascardiac development has also been confirmed in numerous studies, culturemodels, and animal models. (Duff et al., FASEB J., 17:984-992 (2003);Bernabeu et al., J. Cell. Biochem., 102(6): 1375-1388 (2007); U.S. Pat.No. 7,097,836).

Thus, methods which inhibit angiogenesis in a diseased tissue amelioratesymptoms of the disease and, depending upon the disease, can contributeto cure of the disease. In one embodiment, the invention contemplatesinhibition of angiogenesis in a tissue. The extent of angiogenesis in atissue, and therefore the extent of inhibition achieved by the presentmethods, can be evaluated by a variety of methods, such as are describedherein.

The unique specificity of the antibodies which recognize (e.g., bind) anepitope on endoglin and inhibits angiogenesis, provides diagnostic andtherapeutic uses for diseases characterized by angiogenesis(neovascularization), small vessel dilation, and/or excessivevascularization such as described herein. Humanized anti-endoglinantibodies and fragments thereof can be administered to a subject suchas a mammal (e.g., a human), suffering from a medical disorder, e.g.,various forms of ocular diseases characterized byangiogenesis/neovascularization (e.g., macular degeneration, diabeticretinopathy), diabetic nephropathy, chronic inflammatory diseases (e.g.,IBD), rheumatoid arthritis, osteoarthritis, and various forms of cancer(primary tumors and metastases). Provided herein is a method fortreating a subject having an ocular disease characterized byangiogenesis by administering a humanized antibody or fragment thereofdescribed herein that binds endoglin and inhibits angiogenesis. Alsoprovided herein is a method for treating a subject having a chronicinflammatory disease by administering a humanized antibody or fragmentthereof described herein that binds endoglin and inhibits angiogenesis.Examples of such chronic inflammatory diseases include, but are notlimited to, Crohn's disease and ulcerative colitis. Further providedherein is a method for treating a subject having diabetic nephropathy byadministering a humanized antibody or fragment thereof described herein.Provided herein is a method for treating a subject having rheumatoidarthritis or osteoarthritis by administering a humanized antibody orfragment thereof described herein.

One would understand that the anti-endoglin antibodies can be effectivefor treating angiogenesis, it is contemplated herein that a subject canalso be treated with one or more additional angiogenesis inhibitors.

The term “angiogenesis inhibitor” is used herein, for purposes of thespecification and claims, to mean a compound or molecule including, butnot limited to, peptides, proteins, enzymes, polysaccharides,oligonucleotides, DNA, RNA, recombinant vectors, and drugs whichfunction to inhibit angiogenesis. Angiogenesis inhibitors are known inthe art and all types are contemplated herein. Non-limiting examples ofcompounds and molecules include natural and synthetic biomolecules suchas paclitaxel, O-(chloroacetyl-carbonyl) fumagillol (“TNP-470” or “AGM1470”), thrombospondin-1, thrombospondin-2, angiostatin, humanchondrocyte-derived inhibitor of angiogenesis (“hCHIAMP”),cartilage-derived angiogenic inhibitor, platelet factor-4, gro-beta,human interferon-inducible protein 10 (“IP10”), interleukin 12, Ro318220, tricyclodecane-9-yl xanthate (“D609”), irsogladine,8,9-dihydroxy-7-methyl-benzo[b] quinolizinium bromide (“GPA 1734”),medroxyprogesterone, a combination of heparin and cortisone, glucosidaseinhibitors, genistein, thalidomide, diamino-antraquinone, herbimycin,ursolic acid, and oleanolic acid. Non-limiting examples of antibodiesinclude those directed towards molecules such as VEGF, VEGF receptor, ordifferent epitopes of endoglin. Additionally, small molecular inhibitorsof VEGF receptor are known and contemplated herein. Non-limitingexamples of VEGF receptor inhibitors include bevacizumab (AVASTIN®),ranibizumab (Lucentis), aflibercept (VEGF-Trap), sunitinib (Sutent),sorafenib (Nexavar), axitinib, pegaptanib and pazopanib.

The antibodies and antigen-binding fragments described herein can beadministered in combination with VEGF receptor inhibitors forcombination therapy of any of the angiogenesis-related conditions ordiseases described herein. In one non-limiting embodiment, the VEGFreceptor inhibitor is bevacizumab. Exemplary dosage for bevacizumab areabout 7.5, about 10, or about 15 mg/kg, administered every 2 or 3 weeks.

In one non-limiting embodiment, the VEGF receptor inhibitor isranibizumab. Exemplary ocular dosages for ranibizumab include about 0.5mg, administered intravitreally monthly. In one non-limiting embodiment,the VEGF receptor inhibitor is aflibercept (VEGF-Trap). Exemplarydosages for VEGF-Trap include about 0.5—about 10 mg/kg administeredevery 2 or 3 weeks. Exemplary ocular dosages for VEGF-Trap include about0.5—about 2.0 mg administered intravitreally monthly or quarterly.

In another non-limiting embodiment, the VEGF receptor inhibitor issunitinib. Exemplary regimens for sunitinib include about 50 mgadministered for 4 weeks, followed by 2 weeks of no drug. Treatmentregimens can be repeated in a cyclic or acyclic basis.

In another non-limiting embodiment, the VEGF receptor inhibitor issorafenib. Exemplary dosages for sorafenib include about 400 mgadministered daily.

In another non-limiting embodiment the VEGF receptor inhibitor isaxitinib. Exemplary dosages for axitinib include about 3, about 5, orabout 10 mg administered twice daily.

In another non-limiting embodiment the VEGF receptor inhibitor ispegaptanib. Exemplary dosages for pegaptanib include about 0.3—about 3mg administered intravitreally every 6 weeks.

In yet another non-limiting embodiment, the VEGF receptor inhibitor ispazopanib. Exemplary dosages for pazopanib include about 200—about 1000mg administered daily.

Multiple combinations of these VEGF receptor inhibitors can beadministered with the antibodies and antigen-binding fragments describedherein. In one embodiment, combinations may result in the use of lowerdoses for the antibodies or antigen binding fragments described herein,the VEGF receptor inhibitors, or both. Such alterations in dosing mayresult from synergistic effects of the combinations of the antibodiesand antigen-binding fragments described herein with the VEGF receptorinhibitors.

Ocular Conditions Involving Angiogenesis

Macular Degeneration Conditions and Diabetic Retinopathy

In one aspect, the present invention provides a method for treatingdiabetic retinopathy, macular degeneration, choroidal neovascularizationor neovascular glaucoma in a patient by administering to the patient atherapeutically effective amount of any of the compositions providedherein.

Endoglin is a receptor associated with angiogenesis and theextracellular matrix. Macular degeneration (AMD) is the loss ofphotoreceptors in the portion of the central retina, termed the macula,responsible for high-acuity vision. Degeneration of the macula isassociated with abnormal deposition of extracellular matrix componentsand other debris in the membrane between the retinal pigment epitheliumand the vascular choroid. This debris-like material is termed drusen.Drusen is observed with a funduscopic eye examination. Normal eyes mayhave maculas free of drusen, yet drusen may be abundant in the retinalperiphery. The presence of soft drusen in the macula, in the absence ofany loss of macular vision, is considered an early stage of AMD. Maculardegeneration is characterized by choroidal neovascularization (CNV), thedevelopment of abnormal blood vessels beneath the retinal pigmentepithelium (RPE) layer of the retina. These vessels break through theBruch's membrane, disrupting the retinal pigmented epithelium, bleed,and eventually cause macular scarring which results in profound loss ofcentral vision (disciform scarring).

Choroidal neovascularization (CNV) commonly occurs in maculardegeneration in addition to other ocular disorders and is associatedwith proliferation of choroidal endothelial cells, overproduction ofextracellular matrix, and formation of a fibrovascular subretinalmembrane. Retinal pigment epithelium cell proliferation and productionof angiogenic factors appears to effect choroidal neovascularization.

Diabetic retinopathy (DR) is an ocular disorder characterized byexcessive angiogenesis that develops in diabetes due to thickening ofcapillary basement membranes, and lack of contact between pericytes andendothelial cells of the capillaries. Loss of pericytes increasesleakage of the capillaries and leads to breakdown of the blood-retinabarrier. Diabetic retinopathy is the result of microvascular retinalchanges. Hyperglycemia-induced pericyte death and thickening of thebasement membrane lead to incompetence of the vascular walls. Thesedamages change the formation of the blood-retinal barrier and also makethe retinal blood vessels become more permeable. Small bloodvessels—such as those in the eye—are especially vulnerable to poor bloodsugar (blood glucose) control. An over-accumulation of glucose and/orfructose damages the tiny blood vessels in the retina. Macular edema canalso develop when the damaged blood vessels leak fluid and lipids ontothe macula. These fluids make the macula swell, which blurs vision. Thisdamage also results in a lack of oxygen at the retina.

As the disease progresses, the lack of oxygen in the retina stimulatesangiogenesis along the retina and in the clear, gel-like vitreous humourthat fills the inside of the eye. Without timely treatment, these newblood vessels can bleed, cloud vision, and destroy the retina.Fibrovascular proliferation can also cause tractional retinaldetachment. The new blood vessels can also grow into the angle of theanterior chamber of the eye and cause neovascular glaucoma.

Proliferative vitreoretinopathy is associated with cellularproliferation of cellular and fibrotic membranes within the vitreousmembranes and on the surfaces of the retina. Retinal pigment epitheliumcell proliferation and migration is common with this ocular disorder.The membranes associated with proliferative vitreoretinopathy containextracellular matrix components such as collagen types I, II, and IV andfibronectin, and become progressively fibrotic.

Age-related macular degeneration (AMD) and diabetic retinopathy are thetwo leading causes of blindness in the developed world. The recentapproval of the macromolecules LUCENTIS®, AVASTIN®, and MACUGEN® haveimproved the treatment options available for AMD patients. LUCENTIS® isa Fab and AVASTIN® is a monoclonal antibody. They both bind vascularendothelial growth factor (VEGF) and have demonstrated the mostimpressive results to date treating AMD; however, only a minority oftreated patients experience a significant improvement in visual acuity.Anti-angiogenic therapy focused on a target other than VEGF may overcomesome of the limitations associated with agents that target the VEGFpathway.

The humanized antibodies and antigen-binding fragments which bindendoglin and are described herein can be used to treat or preventmacular degeneration, CNV, diabetic retinopathy, or proliferativevitreoretinopathy. Described herein are methods of treating orpreventing macular degeneration, CNV, diabetic retinopathy, orproliferative vitreoretinopathy via the administration of the antibodiesand antigen-binding fragments described herein. The humanized antibodiesand antigen-binding fragments which bind endoglin and are describedherein can also shrink blood vessels, inhibit endothelial cellproliferation associated with ocular disease, clear symptoms ofbleeding, treat cloudy vision, provide stasis of vision loss, and/orprevent leakage of blood vessels. The humanized antibodies andantigen-binding fragments described herein can also be used inmedicaments for the treatment of macular degeneration, CNV, diabeticretinopathy or proliferative vitreoretinopathy.

Additionally, humanized antibodies and antigen-binding fragmentsdescribed herein can also be used in combination with known therapiesand/or compounds for the treatment of macular degeneration, CNV,diabetic retinopathy or proliferative vitreoretinopathy. Examples ofsuch compounds include, but are not limited to, bevacizumab (AVASTIN®),ranibizumab (LUCENTIS®), aflibercept (VEGF-Trap), sunitinib (SUTENT®),sorafenib (NEXAVAR®), axitinib, pegaptanib, pazopanib or MACUGEN®. Inaddition to the modes of administration described herein, the humanizedanti-endoglin antibodies and antigen-binding fragments can beadministered via intravitreal routes. Non-limiting examples ofintravitreal modes of administration include intravitreal injection andthe use of intravitreal implants.

Patients can be assessed for improvement and responsiveness totreatment. Treatment includes, but is not limited to, decreasing themacular edema, decreased areas of CNV, and increased visual acuity.Measurements of symptoms are as known in the art and are furtherdescribed in the examples below.

Chronic Inflammatory Diseases

Any of a variety of tissues or organs comprised of organized tissues,can support angiogenesis in disease conditions including skin, muscle,gut, connective tissue, joints, bones and the like tissue in which bloodvessels can invade upon angiogenic stimuli. Thus, in one embodiment, atissue to be treated is an inflamed tissue and the angiogenesis to beinhibited is inflamed tissue angiogenesis where there isneovascularization of inflamed tissue.

Inflammatory Bowel Diseases

Angiogenesis plays an important role in inflammatory bowel disease(IBD). IBD is an umbrella term for a set of bowel and intestinaldiseases or conditions including Crohn's disease and ulcerative colitis.Crohn's disease is typically characterized by inflammation of the smalland large bowel, whereas ulcerative colitis is generally localized tothe colon. Abnormal or pathological angiogenesis is central to bothCrohn's disease and ulcerative colitis. Both diseases involve increasedmicrovascular density and microvascular dysfunction, and thisangiogenesis is temporally related with tissue pathology and theinflammatory cycles found in both diseases. Endoglin is known to beexpressed in these tissues and to play a role in the dysregulation ofangiogenesis during IBD. (Chidlow et al., Am. J. Physiol. Gastrointest.Liver Physiol., 293:5-18 (2007)).

The humanized antibodies and antigen-binding fragments which bindendoglin and are described herein can be used to treat IBD.Additionally, humanized antibodies and antigen-binding fragments whichbind endoglin can be used for the treatment of Crohn's disease orulcerative colitis. The humanized anti-endoglin antibodies andantigen-binding fragments can also be used in combination with surgeryand/or known therapies for IBD, Crohn's disease or ulcerative colitis.Examples of such known therapies include, but are not limited to,Aminosalicylates (e.g., Mesalamine), corticosteroids (e.g., budesonide,prednisone, etc.), antibiotics (e.g., metronidizole, etc.),immunosuppresive drugs (e.g., azathioprine, 6-mercaptopurine,methotrexate, Tacrolimus, and cyclosporine, etc.), and biologic drugssuch as proteins and antibodies (e.g., infliximab, etc.).

Treatment of IBD can be assessed by decreased vascularization of theinflamed tissue. Treatment can also be assessed by stasis, resolution,and/or healing of the ulcerative lesions which characterize IBD.

Diabetic Nephropathy & Renal Transplantation Ischemia

Diabetic nephropathy is a major cause of morbidity and mortality in bothtype 1 and type 2 diabetics. It is the leading cause of end-stage renaldisease world-wide. Diabetic nephropathy is characterized by glomerularmicrovascular injury due to the increased synthesis of pro-angiogenicfactors. These pro-angiogenic factors cause increased endothelial cellproliferation and subsequent angiogenesis, and endoglin is known to beupregulated in chronic renal disease. This angiogenesis results indestruction of the glomeruli and finally renal failure. (Zent et al.,Seminars in Nephrology, 27(2): 161-171 (2007); Roy-Chaudhury et al.,Exp. Nephrol., 5:55-60 (1997)).

Similar effects are seen in renal transplantation resulting in ischemiaand failure of the transplanted organ. The upregulation of endoglinresults in upregulated angiogenesis and inflammation in the kidney.Conversely, studies with endoglin null mice show significantly reducedrenal damage after transplantation/ischemia and increased organsurvival. (Docherty et al., Nephol. Dial. Transplant., 21:2106-2119(2006)).

The humanized antibodies and antigen-binding fragments which bindendoglin and are described herein can be used to treat or preventdiabetic nephropathy, renal failure following transplantation, and/orischemic renal injury following transplantation.

Described herein are methods of treating or preventing diabeticnephropathy, renal failure following transplantation, and/or ischemicrenal injury following transplantation via the administration of theantibodies and antigen-binding fragments described herein. The humanizedantibodies and antigen-binding fragments described herein can also beused in medicaments for the treatment of diabetic nephropathy, renalfailure following transplantation, and/or ischemic renal injuryfollowing transplantation. Additionally, humanized antibodies andantigen-binding fragments described herein can also be used incombination with known therapies and/or compounds for the treatment ofdiabetic nephropathy, renal failure following transplantation, and/orischemic renal injury following transplantation.

Patients can be assessed with respect to the efficacy of treatment by,for example, improvement in renal function.

Rheumatoid Arthritis & Osteoarthritis

Rheumatoid arthritis is characterized by excessive angiogenesis, and iswell understood in this regard. The inflammation and destruction foundin the synovial fluids is directly related to the increased angiogenesisfound surrounding and in the synovial tissues. Numerous pro-angiogenicfactors are present in the affected tissues of rheumatoid arthritispatients. (Koch and Distler, Arthritis Res. & Ther., 9 (Suppl. 2): S3,1-9 (2007).

Osteoarthritis is a group of chronic disabling conditions that affectsthe synovial joints. Angiogenesis and inflammation are integralprocesses in the pathophysiology of the disease, and they contribute tojoint damage through a variety of mechanisms, including but not limitedto, stimulation of MMP production and endochondral ossification.Additionally, angiogenesis in osteoarthritis induces furtherinnervation, which develops into a feedback loop where each continues tostimulate the other. (Bonnet & Walsh, Rheumatology, 44:7-16 (2005)).

The humanized antibodies and antigen-binding fragments which bindendoglin and are described herein can be used to treat or preventrheumatoid arthritis and osteoarthritis. Described herein are methods oftreating or preventing rheumatoid arthritis and osteoarthritis via theadministration of the antibodies and antigen-binding fragments describedherein. The humanized antibodies and antigen-binding fragments describedherein can also be used in medicaments for the treatment of rheumatoidarthritis and osteoarthritis.

Two well accepted composite measures of improvement of RA in trials are:the Paulus Criteria and The American College of Rheumatology Criteria(ACR). Paulus Criteria is defined as improvement in 4 of the following:tender and swollen joint counts, morning stiffness, patient assessmentof disease activity, physician assessment of disease activity anderythrocyte sedimentation rate (ESR) rage. The level of improvement isset as a percentage improvement of each of these variables i.e. a Paulus20 classification indicates a responder who has shown 20% improvement in4 of the 6 parameters.

Rheumatoid arthritis can also be assessed using American College ofRheumatology (ACR) Scoring. Briefly, ACR Classification Criteria forDetermining Clinical Remission in Rheumatoid Arthritis is assessed bythe presence of 5 or more of the following factors present at least twoconsecutive months:

-   -   a. Morning stiffness <15 minutes;    -   b. No fatigue;    -   c. No joint pain;    -   d. No joint tenderness or pain on motion;    -   e. No soft tissue swelling in joints or tendon sheaths; and    -   f. ESR (Westergren method)<30 mm/hour for a female or 20 mm/hour        for a male.

Exclusions may occur and include: clinical manifestations of activevasculitis, pericarditis, pleuritis or myositis, and unexplained recentweight loss or fever attributable to rheumatoid arthritis will prohibita designation of complete clinical remission (Pinals R S, et. al.:Arthritis Rheum 24:1308, 1981). Additionally, ACR ClassificationCriteria of Functional Status in Rheumatoid Arthritis includesclassification based on the following patient abilities:

-   -   Class I: Completely able to perform usual activities of daily        living (self-care, vocational, and avocational);    -   Class II: Able to perform usual self-care and vocational        activities, but limited in avocational activities;    -   Class III: Able to perform usual self-care activities, but        limited in vocational and avocational activities; and    -   Class IV: Limited ability to perform usual self-care,        vocational, and avocational activities.

Osteoarthritis can also be assessed using ACR scoring. ACR ClinicalClassification Criteria for Osteoarthritis of the hip is assessedutilizing patient history, physical examination and laboratory findings:a patient is assessed for pain in the hip and one of the following:

-   -   (1) Internal hip rotation of less than 15 degrees and ESR less        than or equal to 45 degrees mm/hour or hip flexion less than or        equal to 115 degrees if ESR is unavailable; or    -   (2) Internal hip rotation of less than 15 degrees, pain        associated with internal hip, morning stiffness of the hip for        less than or equal to 60 minutes and the patient is over 50        years of age.

Using history, physical examination, laboratory and radiographicfindings, traditional format is pain in the hip and two of the followingindications: ESR less than 20 mm/hour, radiographic femoral and/oracetabular osteophytes, or radiographic joint space narrowing (superior,axial, and/or medial). A classification tree is as follows: pain in thehip in association with (1) radiographic femoral and/or acetabularosteophytes or (2) ESR less than or equal to 20 mm/hour and radiographicaxial joint space narrowing (Altman, R, et al.: Arthritis Rheum 34:505,1991).

ACR Clinical Classification Criteria for Osteoarthritis of the knee

ACR Clinical Classification Criteria for Osteoarthritis of the knee isassessed using history and physical examination utilizing the followingcriteria: pain in the knee in connection with three (3) of thefollowing:

-   -   (1) a patient is over 50 years of age;    -   (2) less than 30 minutes of morning stiffness;    -   (3) Crepitus on active motion;    -   (4) bony tenderness;    -   (5) bony enlargement; and    -   (6) no palpable warmth of synovium.

Using patient history, physical examination and radiographic findings,pain in the knee can be assessed in connection with one of the followingpatient characteristics: (1) a patient is over 50 years of age; (2) lessthan 30 minutes of morning stiffness; and (3) Crepitus on active motionand osteophytes. Using history, physical examination and laboratoryfindings: pain in the knee can be assessed inn connection with five (5)of the following characteristics:

-   -   (1) a patient is over 50 years of age;    -   (2) less than 30 minutes of morning stiffness;    -   (3) Crepitus on active motion;    -   (4) bony tenderness;    -   (5) bony enlargement;    -   (6) No palpable warmth of synovium;    -   (7) ESF is less than 40 mm/hour;    -   (8) Rheumatoid factor (RF) of less than 1:40; and    -   (9) Synovial Fluid (SF) signs of osteoarthritis.

See, e.g., Altman, R, et al.: Arthritis Rheum 29:1039, 1986.

ACR Clinical Classification Criteria for Osteoarthritis of the hand canbe assessed as follows: pain, aching or stiffness in the hand inconnection with three (3) of the following: (1) hard tissue enlargementof two or more of the following joints (second and third distalinterphalangeal, the second and third proximal interphalangeal, and thefirst carpometacarpal joints of both hands; (2) hard tissue enlargementof two or more distal interphalangeal joints; (3) less than threeswollen MCP joints and (4) deformity of at least one of the jointslisted above in (1).

Cancer

CD105 is associated with tumor angiogenesis and is strongly up-regulatedin the endothelium of various tumor tissues compared with that in normaltissues. CD105 is up-regulated in a wide range of tumor endotheliaincluding, for example, colon, breast, brain, lung, prostate,endometrial, kidney, liver, gastric, head & neck and cervical cancer.Additionally, it is known that there is stronger expression of CD105 intumor endothelium than corresponding normal tissues. (Duff et al., FASEBJ., 17:984-992 (2003); Bernabeu et al., J. Cell. Biochem., 102(6):1375-1388 (2007); U.S. Pat. No. 7,097,836). Thus, the inhibition ofangiogenesis with anti-endoglin humanized antibodies represents atreatment option for cancerous tumors. The humanized antibodies andantigen-binding fragments which bind endoglin and are described hereincan be used to treat cancerous tumors. The humanized antibodies andantigen-binding fragments described herein can also be used inmedicaments for the treatment cancerous tumors.

The term “tumor” is used herein to refer to a cancerous tissueexpressing endoglin (as compared to expression by normal tissue of thesame type). Tumors can include solid tumors and semi-solid tumors.Non-limiting examples of tumors include human leukemias, includingnon-T-cell-type (non-T) acute lymphoblastic leukemia (ALL),myelo-monocytic leukemia; and human solid and semi-solid tumors, withits surrounding vasculature expressing endoglin at moderate to highlevels (as compared to expression by normal tissue of the same type)including angiosarcoma, breast carcinoma, stomach cancer, coloncarcinoma, Hodgkins lymphoma, lymphoma, glioblastoma multiforme (GBM),lung carcinoma, melanoma, myeloma, lymphoma, osteosarcoma, ovariancarcinoma, parotid tumor, pharyngeal carcinoma, prostate carcinoma,hepatocellular carcinoma, renal carcinoma, and rectosigmoid carcinoma.

A cancerous tissue to be treated is, for example, an endothelial tissueexpressing an abnormal level of endoglin.

In the absence of neovascularization of tumor tissue, the tumor tissuedoes not obtain the required nutrients, slows in growth, ceasesadditional growth, regresses and ultimately becomes necrotic resultingin killing of the tumor. The present invention provides for a method ofinhibiting tumor neovascularization by inhibiting tumor angiogenesisaccording to the present methods. Similarly, the invention provides amethod of inhibiting tumor growth by practicing theangiogenesis-inhibiting methods.

The methods are also particularly effective against the formation ofmetastases because their formation requires vascularization of a primarytumor so that the metastatic cancer cells can exit the primary tumor andtheir establishment in a secondary site requires neovascularization tosupport growth of the metastases.

It will be appreciated that a “patient suffering from acancer/metastasis” of the invention may express a mutant protein (tumorassociated antigen) or a mutant gene and not yet be symptomatic for thedisease. In one non-limiting example, where the cancer is colon cancer(which is associated with the mutant K-ras protein), a patient with amutant K-ras protein in some cells of the colon is a patient accordingto the invention even though that patient may not yet be symptomatic forcolon cancer. “Signs or symptoms of illness” are clinically recognizedmanifestations or indications of disease.

By “treating” a patient suffering from cancer it is meant that thepatient's symptoms are partially or totally alleviated, or remain staticfollowing treatment according to the invention. A patient that has beentreated can exhibit a partial or total alleviation of symptoms and/ortumor load. This is intended to encompass prophylaxis, therapy and cure.In one non-limiting example, a patient suffering from a highlymetastatic cancer (e.g., breast cancer) is treated where additionalmetastasis either do not occur, or are reduced in number as compared toa patient who does not receive treatment. In another non-limitingexample, a patient is treated where the patient's solid cancer eitherbecomes reduced in size or does not increase in size as compared to apatient who does not receive treatment. In yet another non-limitingexample, the number of cancer cells in a treated patient either does notincrease or is reduced as compared to the number of cancer cells in apatient who does not receive treatment. Improvement can also be defined,for example, as decreased cell proliferation, decreased numbers ofcells, increased apoptosis, and/or increased survival of the patientbeing treated.

As further used herein, treatment of cancer includes stasis, partial ortotal elimination of a cancerous growth or tumor. Treatment or partialelimination includes, for example, a fold reduction in growth or tumorsize and/or volume such as about 2-fold, about 3-fold, about 4-fold,about 5-fold, about 10-fold, about 20-fold, about 50-fold, or any foldreduction in between. Similarly, treatment or partial elimination caninclude a percent reduction in growth or tumor size and/or volume ofabout 1%, 2%, 3%, 4%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%,95% or any percentage reduction in between.

A tumor or cancer to be treated in the methods described hereinincludes, but is not limited to, a lung cancer, a gynecologicmalignancy, a melanoma, a breast cancer, a brain cancer (e.g.,glioblastoma multiforme, “GBM”) a pancreatic cancer, an ovarian cancer,a uterine cancer, a colorectal cancer, a prostate cancer, a kidneycancer, a head cancer, a liver cancer (hepatocellular cancer), a uterinecancer, a neck cancer, a kidney cancer (renal cell cancer), a sarcoma, amyeloma, and lymphoma. In one embodiment, a tumor to be treated is asolid or semi-solid tumor. In another embodiment, a tumor to be treatedis a primary tumor. In another embodiment, a tumor to be treated is ametastatic tumor. In one embodiment, a tumor or cancer to be treated isof epithelial origin. In another embodiment, the cancer to be treated ismyeloma. In another embodiment, the cancer to be treated is ovariancancer. In another embodiment, the cancer to be treated is kidney/renalcancer. In yet another embodiment, the cancer to be treated ishepatocellular/liver cancer.

Lung Cancer

In one aspect, provided herein is a method to treat lung cancer. Themost common type of lung cancer is non-small cell lung cancer (NSCLC),which accounts for approximately 80-85% of lung cancers and is dividedinto squamous cell carcinomas, adenocarcinomas, and large cellundifferentiated carcinomas. Small cell lung cancer accounts for 15-20%of lung cancers.

Lung cancer staging is an assessment of the degree of spread of thecancer from its original source. It is an important factor affecting theprognosis and potential treatment of lung cancer. Non-small cell lungcarcinoma is staged from IA (“one A”; best prognosis) to IV (“four”;worst prognosis). Small cell lung carcinoma is classified as limitedstage if it is confined to one half of the chest and within the scope ofa single radiotherapy field; otherwise, it is extensive stage.

Non-small cell lung cancer may be staged using EUS (endoscopicultrasound) or CT or MRI scan or at surgery to classify the extent ofdisease according to the TNM system. These subjects undergo staging aspart of the process of considering prognosis and treatment. The AJCCrecommends TNM staging followed by further grouping.

Primary tumor (T): TX: The primary tumor cannot be assessed, or thereare malignant cells in the sputum or bronchoalveolar lavage but not seenon imaging or bronchoscopy; Tis: Carcinoma in situ. T0: No evidence ofprimary tumor. T1: Tumor less than 3 cm in its greatest dimension,surrounded by lung or visceral pleura and without bronchoscopic invasioninto the main bronchus. T2: A tumor with any of: more than 3 cm ingreatest dimension; extending into the main bronchus (but more than 2 cmdistal to the carina), and obstructive pneumonitis (but not involvingthe entire lung). T3: A tumor with any of: invasion of the chest wall,diaphragm, mediastinal pleura, or parietal pericardium; extending intothe main bronchus, within 2 cm of the carina, but not involving thecarina; and obstructive pneumonitis of the entire lung. T4: A tumor withany of: invasion of the mediastinum, heart, great vessels, trachea,esophagus, vertebra, or carina; separate tumor nodules in the same lobe;and malignant pleural effusion. Lymph nodes (N): NX: Lymph nodes cannotbe assessed; N0: No lymph nodes involved; N1: Metastasis to ipsilateralperibronchial or ipsilateral hilar lymph nodes; N2: Metastasis toipsilateral mediastinal or subcarinal lymph nodes; and N3: Metastasis toany of: ipsilateral supraclavicular lymph nodes; ipsilateral scalenelymph nodes; and contralateral lymph nodes. Distant metastasis (M): MX:Distant metastasis cannot be assessed; M0: No distant metastasis; andM1: Distant metastasis is present.

Uterine cancers/Gynecologic Malignancy

Uterine cancers may refer to any of several different types of cancerwhich occur in the uterus, namely: uterine sarcomas (e.g., sarcomas ofthe myometrium, or muscular layer of the uterus, are most commonlyleiomyosarcomas); endometrial cancer; and cervical cancer.

In another aspect, provided herein is a method to treat endometriumcancer. Endometrial cancer is a cancer that starts in the endometrium,the inner lining of the uterus. Some of the examples of the cancer ofuterus and endometrium include, but are not limited to, adenocarcinomas,adenoacanthomas, adenosquamous carcinomas, papillary serousadenocarcinomas, clear cell adenocarcinomas, uterine sarcomas, stromalsarcomas, malignant mixed mesodermal tumors, and leiomyosarcomas.

In another aspect, the method treats cervical cancer, preferably anadenocarcinoma in the cervix epithelial. Two main types of this cancerexist: squamous cell carcinoma and adenocarcinomas. The formerconstitutes about 80-90% of all cervical cancers and develops where theectocervix (portion closest to the vagina) and the endocervix (portionclosest to the uterus) join. The latter develop in the mucous-producinggland cells of the endocervix. Some cervical cancers havecharacteristics of both of these and are called adenosquamous carcinomasor mixed carcinomas.

Ovarian Cancer

In another aspect, provided herein is a method of treating ovariancancer, including epithelial ovarian tumors.

Ovarian cancer is classified according to the histology of the tumor,obtained in a pathology report. Surface epithelial-stromal tumor, alsoknown as ovarian epithelial carcinoma, is the most typical type ofovarian cancer. It includes serous tumor, endometrioid tumor andmucinous cystadenocarcinoma. Sex cord-stromal tumor, includingestrogen-producing granulosa cell tumor and virilizing Sertoli-Leydigcell tumor or arrhenoblastoma, accounts for 8% of ovarian cancers. Germcell tumor accounts for approximately 30% of ovarian tumors but only 5%of ovarian cancers because most germ cell tumors are teratomas and mostteratomas are benign. Germ cell tumor tends to occur in young women andgirls. The prognosis depends on the specific histology of germ celltumor, but overall is favorable. Mixed tumors contain elements of morethan one of the above classes of tumor histology.

Ovarian cancer can also be a secondary cancer, the result of metastasisfrom a primary cancer elsewhere in the body. Common primary cancers arebreast cancer and gastrointestinal cancer (in which case the ovariancancer is a Krukenberg cancer). Surface epithelial-stromal tumor canoriginate in the peritoneum (the lining of the abdominal cavity), inwhich case the ovarian cancer is secondary to primary peritoneal cancer,but treatment is basically the same as for primary surfaceepithelial-stromal tumor involving the peritoneum.

Ovarian cancer staging is by the FIGO staging system and usesinformation obtained after surgery, which can include a total abdominalhysterectomy, removal of both ovaries and fallopian tubes, the omentum,and pelvic (peritoneal) washings for cytology. The AJCC stage is thesame as the FIGO stage.

Stage I refers to ovarian cancer limited to one or both ovaries:IA—involves one ovary; capsule intact; no tumor on ovarian surface; nomalignant cells in ascites or peritoneal washings; IB—involves bothovaries; capsule intact; no tumor on ovarian surface; negative washings;and IC—tumor limited to ovaries with any of the following: capsuleruptured, tumor on ovarian surface, positive washings.

Stage II refers to pelvic extension or implants: IIA—extension orimplants onto uterus or fallopian tube; negative washings; IIB—extensionor implants onto other pelvic structures; negative washings; andIIC—pelvic extension or implants with positive peritoneal washings

Stage III refers to microscopic peritoneal implants outside of thepelvis; or limited to the pelvis with extension to the small bowel oromentum: IIIA—microscopic peritoneal metastases beyond pelvis;IIIB—macroscopic peritoneal metastases beyond pelvis less than 2 cm insize; and IIIC—peritoneal metastases beyond pelvis >2 cm or lymph nodemetastases

Stage IV refers to distant metastases to the liver or outside theperitoneal cavity.

Para-aortic lymph node metastases are considered regional lymph nodes(Stage IIIC).

In some embodiments, the methods described herein treat an ovariancancer selected from the following: an adenocarcinoma in the ovary andan adenocarcinoma that has migrated from the ovary into the abdominalcavity.

Melanoma

A melanoma is a malignant tumor of melanocytes which are foundpredominantly in skin but also in the bowel and the eye (uvealmelanoma). It is one of the rarer types of skin cancer but causes themajority of skin cancer related deaths. Malignant melanoma is a serioustype of skin cancer caused by uncontrolled growth of pigment cells,called melanocytes. Melanomas also include, but are not limited to, achoroidea melanoma, malignant melanomas, cutaneous melanomas andintraocular melanomas.

Melanoma may be divided into the following types: Lentigo maligna,Lentigo maligna melanoma, superficially spreading melanoma, acrallentiginous melanoma, mucosal melanoma, nodular melanoma, polypoidmelanoma, desmoplastic melanoma, amelanotic melanoma, soft-tissuemelanoma, and uveal melanoma. Melanoma stages are as follows:

Stage 0—melanoma in situ (Clark Level I).

Stage I/II—invasive melanoma: T1a: less than 1.00 mm primary, withoutulceration, Clark Level II-III; T1b: less than 1.00 mm primary, withulceration or Clark Level IV-V; and T2a: 1.00-2.00 mm primary, withoutulceration.

Stage II—High Risk Melanoma: T2b: 1.00-2.00 mm primary, with ulceration;T3a: 2.00-4.00 mm primary, without ulceration; T3b: 2.00-4.00 mmprimary, with ulceration; T4a: 4.00 mm or greater primary withoutulceration; and T4b: 4.00 mm or greater primary with ulceration.

Stage III—Regional Metastasis: N1: single positive lymph node; N2: 2-3positive lymph nodes or regional skin/in-transit metastasis; and N3: 4positive lymph nodes or lymph node and regional skin/in transitmetastases.

Stage IV—Distant Metastasis: M1a: Distant Skin Metastasis, Normal LDH;M1b: Lung Metastasis, Normal LDH; and M1c: Other Distant Metastasis ORAny Distant Metastasis with Elevated LDH.

In one embodiment, the methods described herein treat a melanoma.

Colon Cancer and Colorectal Cancer

Colorectal cancer (also called colon cancer or large bowel cancer)includes cancerous growths in the colon, rectum (anus) and appendix.With 655,000 deaths worldwide per year, it is the third most common formof cancer and the second leading cause of cancer-related death in theWestern world. Many colorectal cancers are thought to arise fromadenomatous polyps in the colon. These mushroom-like growths are usuallybenign, but some may develop into cancer over time.

In another embodiment, Dukes classification may be used to classifycolorectal cancer based on stages A-D. Stage A refers to colorectalcancer that is limited to mucosa (i.e., has not invaded through thebowel wall). Stage B1 refers to extending into muscularis propria, butnot penetrating through it (i.e., lymph nodes have not been invaded);whereas Stage B2 cancer has penetrated through the muscularis propria,but not penetrating through it (i.e., lymph nodes have not beeninvaded). Stage C1 refers to cancer that extends into the muscularispropria, but not penetrating through it (i.e., lymph nodes areinvolved); whereas Stage C2 refers to cancer that extends into themuscularis propria and penetrating through it (i.e., lymph nodes areinvolved). Stage D refers to distant metastatic spread. The TNM systemmay also be used to stage colorectal cancer according to conventionalmeans known in the art.

Breast Cancer

Several types of breast cancer exist that may be treated by the methodsdescribed herein. A lobular carcinoma in situ and a ductal carcinoma insitu are breast cancers that have developed in the lobules and ducts,respectively, but have not spread to the fatty tissue surrounding thebreast or to other areas of the body. Infiltrating (or invasive) lobularand ductal carcinoma are cancers that have developed in the lobules andducts, respectively, and have spread to either the breast's fatty tissueand/or other parts of the body. In one aspect, provided herein is amethod of treating breast cancer, such as a ductal carcinoma in ducttissue in a mammary gland, a breast cancer that is Her2- and/or ER-and/or PR-. Other cancers of the breast that would benefit fromtreatment by the methods are medullary carcinomas, colloid carcinomas,tubular carcinomas, and inflammatory breast cancer.

In one embodiment, breast cancer is staged according to the TNM system.Prognosis is closely linked to results of staging, and staging is alsoused to allocate patients to treatments both in clinical trials andclinical practice.

Briefly, the information for staging is as follows: TX: Primary tumorcannot be assessed. T0: No evidence of tumor. T is: Carcinoma in situ,no invasion; T1: Tumor is 2 cm or less; T2: Tumor is more than 2 cm butnot more than 5 cm; T3: Tumor is more than 5 cm; T4: Tumor of any sizegrowing into the chest wall or skin, or inflammatory breast cancer. NX:Nearby lymph nodes cannot be assessed N0: cancer has not spread toregional lymph nodes. N1: cancer has spread to 1 to 3 maxillary or oneinternal mammary lymph node N2: cancer has spread to 4 to 9 maxillarylymph nodes or multiple internal mammary lymph nodes N3: One of thefollowing applies: cancer has spread to 10 or more maxillary lymphnodes, or cancer has spread to the lymph nodes under the clavicle(collar bone), or cancer has spread to the lymph nodes above theclavicle, or cancer involves maxillary lymph nodes and has enlarged theinternal mammary lymph nodes, or cancer involves 4 or more maxillarylymph nodes, and tiny amounts of cancer are found in internal mammarylymph nodes on sentinel lymph node biopsy. MX: presence of distantspread (metastasis) cannot be assessed. M0: no distant spread. M1:spread to distant organs (not including the supraclavicular lymph node)has occurred.

Pancreatic Cancer

In another aspect, provided herein is a method of treating pancreaticcancer selected from the following: an epithelial carcinoma in thepancreatic duct tissue and an adenocarcinoma in a pancreatic duct. Themost common type of pancreatic cancer is an adenocarcinoma, which occursin the lining of the pancreatic duct.

In one embodiment, the methods described herein treat a pancreaticcancer.

Prostate Cancer

In one other aspect, provided herein is a method to treat prostatecancer selected from the following: an adenocarcinoma or anadenocarcinoma that has migrated to the bone. Prostate cancer developsin the prostate organ in men, which surrounds the first part of theurethra. The prostate has several cell types but 99% of tumors areadenocarcinomas that develop in the glandular cells responsible forgenerating seminal fluid.

There are two schemes commonly used to stage prostate cancer. The mostcommon is the TNM system, which evaluates the size of the tumor, theextent of involved lymph nodes, and any metastasis (distant spread). Aswith many other cancers, these are often grouped into four stages(I-IV). Another scheme, used less commonly, is the Whitmore-Jewettstage.

Briefly, Stage I disease is cancer that is found incidentally in a smallpart of the sample when prostate tissue was removed for other reasons,such as benign prostatic hypertrophy, and the cells closely resemblenormal cells and the gland, feels normal to the examining finger. InStage II more of the prostate is involved and a lump can be felt withinthe gland. In Stage III, the tumor has spread through the prostaticcapsule and the lump can be felt on the surface of the gland. In StageIV disease, the tumor has invaded nearby structures, or has spread tolymph nodes or other organs. Grading is based on cellular content andtissue architecture from biopsies (Gleason) which provides an estimateof the destructive potential and ultimate prognosis of the disease.

In one embodiment, the methods described herein treat a prostate cancer.

Head and Neck Cancers

Head and neck cancers (e.g., oral, laryngeal, nasopharyngeal,esophageal, etc.), refer to a group of biologically similar cancersoriginating from the upper aerodigestive tract, including the lip, oralcavity (mouth), nasal cavity, paranasal sinuses, pharynx, and larynx.Most head and neck cancers are squamous cell carcinomas, originatingfrom the mucosal lining (epithelium) of these regions. Head and neckcancers often spread to the lymph nodes of the neck, and this is oftenthe first (and sometimes only) manifestation of the disease at the timeof diagnosis. Head and neck cancer is strongly associated with certainenvironmental and lifestyle risk factors, including tobacco smoking,alcohol consumption, and certain strains of the sexually transmittedhuman papillomavirus. Management of patients with head and neck cancersremains a formidable task. Cancers such as, hypopharyngeal cancer,laryngeal cancer, nasopharyngeal cancer, oropharyngeal cancer, may betreated using the compounds described herein.

In one embodiment, the methods described herein treat a head or neckcancer.

Kidney Cancer

In another aspect, provided herein is a method to treat kidney cancer.Kidney cancer (also called renal cell cancer, renal cell carcinoma,renal adenocarcinoma, and hypernephroma) is a disease in which malignantcells are found in the lining of tubules in the kidney. Renal cellcarcinoma is the most common form of kidney cancer arising from theproximal renal tubule. It is the most common type of kidney cancer inadults, responsible for approximately 80% of cases.

In one embodiment, the methods described herein treat a kidney cancer.

Liver Cancer

In another aspect, provided herein is a method to treat primary livercancer (cancer that begins in the liver). Primary liver cancer can occurin both adults and children. Liver cancer is characterized by thepresence of malignant hepatic tumors—tumors or growths on or in theliver. They may be discovered on medical imaging (even for a differentreason than the cancer itself), or may be present in patients as anabdominal mass, abdominal pain, jaundice, or some other liverdysfunction. There are several types of liver cancer.

Hemangiomas: These are the most common type of benign liver tumor. Theystart in blood vessels. Most of these tumors do not cause symptoms, theydo not need treatment. Some may bleed and need to be removed if it ismild to severe.

Hepatic adenomas: These benign epithelial liver tumors develop in theliver. They are, in most cases, located in the right hepatic lobe andare frequently seen as solitary. The size of adenomas range from 1 to 30cm. Symptoms associated with hepatic adenomas are all associated withlarge lesions which can cause intense abdominal pain.

Focal nodular hyperplasia: Focal nodular hyperplasia (FNH) is the secondmost common tumor of the liver. This tumor is the result of a congenitalarteriovenous malformation hepatocyte response. This process is one inwhich all normal constituents of the liver are present, but the patternby which they are presented is abnormal. Even though those conditionsexist the liver still seems to perform in the normal range.

Hepatocellular Cancer: Hepatocellular cancer (HCC) is the most commoncancer of the liver. It is associated with alcohol abuse and hepatitis Binfection and is particularly prevalent in Asia. The majority of HCC isdetected at a time when cure by surgical resection is not possible;systemic treatment of un-resectable HCC is associated with survival ofless than one year.

In one embodiment, the methods described herein treat a liver cancer.

Lymphoma

Lymphoma is a type of cancer that originates in lymphocytes of theimmune system. They often originate in lymph nodes, presenting as anenlargement of the node (a tumor). Lymphomas are closely related tolymphoid leukemias, which also originate in lymphocytes but typicallyinvolve only circulating blood and the bone marrow (where blood cellsare generated in a process termed haematopoiesis) and do not usuallyform tumors. There are many types of lymphomas, and in turn, lymphomasare a part of the broad group of diseases called hematologicalneoplasms. Some forms of lymphoma are indolent (e.g. small lymphocyticlymphoma), compatible with a long life even without treatment, whereasother forms are aggressive (e.g. Burkitt's lymphoma), causing rapiddeterioration and death.

The WHO Classification, published in 2001 and updated in 2008;http://en.wikipedia.org/wiki/Lymphoma-cite_note-isbn92-832-2411-6-2#cite_note-isbn92-832-2411-6-2is the latest classification of lymphoma and is based upon thefoundations laid within the “Revised European-American Lymphomaclassification” (REAL). This system groups lymphomas by cell type (i.e.,the normal cell type that most resembles the tumor) and definingphenotypic, molecular or cytogenetic characteristics. There are threelarge groups: the B cell, T cell, and natural killer cell tumors. Otherless common groups are also recognized. Hodgkin's lymphoma, althoughconsidered separately within the WHO (and preceding) classifications, isnow recognized as being a tumor of, albeit markedly abnormal,lymphocytes of mature B cell lineage.

In one embodiment, the methods described herein treat a lymphoma.

Sarcoma

A sarcoma is a cancer of the connective tissue (bone, cartilage, fat)resulting in mesoderm proliferation.

This is in contrast to carcinomas, which are of epithelial origin(breast, colon, pancreas, and others). However, due to an evolvingunderstanding of tissue origin, the term “sarcoma” is sometimes appliedto tumors now known to arise from epithelial tissue. The term softtissue sarcoma is used to describe tumors of soft tissue, which includeselements that are in connective tissue, but not derived from it (such asmuscles and blood vessels).

Sarcomas are given a number of different names, based on the type oftissue from which they arise. For example, osteosarcoma arises frombone, chondrosarcoma arises from cartilage, and leiomyosarcoma arisesfrom smooth muscle. Sarcomas strike people in all age ranges, but theyare very rare, accounting for only 1% of all cases of cancer. GIST isthe most common form of sarcoma, with approximately 3000-3500 cases peryear in the United States. This should be compared with breast cancer,with approximately 200,000 cases per year in North America.

Approximately 50% of bone sarcomas and 20% of soft tissue sarcomas arediagnosed in people under the age of 35. Some sarcomas, such asleiomyosarcoma, chondrosarcoma, and gastrointestinal stromal tumor(GIST), are more common in adults than in children. Most high grade bonesarcomas, including Ewing's sarcoma and osteosarcoma, are much morecommon in children and young adults.

In one embodiment, the methods described herein treat a sarcoma.

Carcinoma

A carcinoma is any malignant cancer that arises from epithelial cells.Carcinomas invade surrounding tissues and organs and may metastasize, orspread, to lymph nodes and other sites.

Carcinoma, like all neoplasia, is classified by its histopathologicalappearance. Adenocarcinoma and squamous cell carcinoma, two commondescriptive terms for tumors, reflect the fact that these cells may haveglandular or squamous cell appearances respectively. Severely anaplastictumors might be so undifferentiated that they do not have a distincthistological appearance (undifferentiated carcinoma).

Sometimes a tumor is referred to by the presumptive organ of the primary(e.g., carcinoma of the prostate) or the putative cell of origin(hepatocellular carcinoma, renal cell carcinoma).

Adenocarcinoma is a malignant tumor originating in the epithelial cellsof glandular tissue and forming glandular structures. This is common inthe lung (forming 30-40% of all lung carcinomas). It is foundperipherally, arising from goblet cells or type II pneumocytes.

Squamous cell carcinoma results from squamous metaplasia. This accountsfor 20-30 percent of lung tumors and is usually hilar in origin.

Small cell carcinoma is almost certainly due to smoking. Thesemetastasize early, and may secrete ADH (lowering patient sodiumconcentration).

Large cell undifferentiated carcinomas account for 10-15 percent of lungneoplasms. These are aggressive and difficult to recognize due to theundifferentiated nature. These are most commonly central in the lung.

Sinonasal undifferentiated carcinoma.

In one embodiment, the methods described herein treat a carcinoma.

Myeloma

Multiple myeloma (also known as MM, myeloma, plasma cell myeloma, or asKahler's disease after Otto Kahler) is a cancer of plasma cells. Theseimmune cells are formed in bone marrow, are numerous in lymphatics andproduce antibodies. Myeloma is regarded as incurable, but remissions maybe induced with steroids, chemotherapy, thalidomide and stem celltransplants. Myeloma is part of the broad group of diseases calledhematological malignancies.

Multiple myeloma develops in post-germinal center B lymphocytes. Achromosomal translocation between the immunoglobulin heavy chain gene(on the fourteenth chromosome, locus 14q32) and an oncogene (often11q13, 4p16.3, 6p21, 16q23 and 20q11) is frequently observed in patientswith multiple myeloma. This mutation results in dysregulation of theoncogene which is thought to be an important initiating event in thepathogenesis of myeloma. The result is proliferation of a plasma cellclone and genomic instability that leads to further mutations andtranslocations. The chromosome 14 abnormality is observed in about 50%of all cases of myeloma. Deletion of (parts of) the thirteenthchromosome is also observed in about 50% of cases.

Production of cytokines (especially IL-6) by the plasma cells causesmuch of their localized damage, such as osteoporosis, and creates amicroenvironment in which the malignant cells thrive. Angiogenesis (theattraction of new blood vessels) is increased.

In one embodiment, the methods described herein treat a myeloma.

Stomach Cancer

Stomach or gastric cancer can develop in any part of the stomach and mayspread throughout the stomach and to other organs; particularly theesophagus, lungs and the liver. Stomach cancer causes about 800.000deaths worldwide per year.

Metastasis occurs in 80-90% of individuals with stomach cancer, with asix month survival rate of 65% in those diagnosed in early stages andless than 15% of those diagnosed in late stages.

Stomach cancer is often asymptomatic or causes only nonspecific symptomsin its early stages. By the time symptoms occur, the cancer hasgenerally metastasized to other parts of the body, one of the mainreasons for its poor prognosis.

In one embodiment, the methods described herein treat a stomach cancer.

Thyroid Cancer

Thyroid neoplasm or thyroid cancer usually refers to any of four kindsof malignant tumors of the thyroid gland: papillary, follicular,medullary or anaplastic. Papillary and follicular tumors are the mostcommon. They grow slowly and may recur, but are generally not fatal inpatients under 45 years of age. Medullary tumors have a good prognosisif restricted to the thyroid gland and a poorer prognosis if metastasisoccurs. Anaplastic tumors are fast-growing and respond poorly totherapy.

Thyroid cancer is usually found in a euthyroid patient, but symptoms ofhyperthyroidism or hypothyroidism may be associated with a large ormetastatic well-differentiated tumor. Nodules are of particular concernwhen they are found in those under the age of 20. The presentation ofbenign nodules at this age is less likely, and thus the potential formalignancy is far greater.

Thyroid cancers can be classified according to their pathologicalcharacteristics. The following variants can be distinguished(distribution over various subtypes may show regional variation):papillary thyroid cancer (up to 75%); follicular thyroid cancer (up to15%); medullary thyroid cancer (up to 8%); and anaplastic thyroid cancer(less than 5%). The follicular and papillary types together can beclassified as “differentiated thyroid cancer”. These types have a morefavorable prognosis than the medullary and undifferentiated types.Thyroid adenoma is a benign neoplasm of the thyroid.

In one embodiment, the methods described herein treat a thyroid cancer.

Bladder Cancer

Bladder cancer refers to any of several types of malignant growths ofthe urinary bladder. It is a disease in which abnormal cells multiplywithout control in the bladder. The bladder is a hollow, muscular organthat stores urine; it is located in the pelvis. The most common type ofbladder cancer begins in cells lining the inside of the bladder and iscalled transitional cell carcinoma (sometimes urothelial cellcarcinoma).

90% of bladder cancers are transitional cell carcinoma. The other 10%are squamous cell carcinoma, adenocarcinoma, sarcoma, small cellcarcinoma and secondary deposits from cancers elsewhere in the body.

The following stages are used to classify the location, size, and spreadof the cancer, according to the TNM (tumor, lymph node, and metastasis)staging system: Stage 0: Cancer cells are found only on the inner liningof the bladder. Stage I: Cancer cells have proliferated to the layerbeyond the inner lining of the urinary bladder but not to the muscles ofthe urinary bladder. Stage II: Cancer cells have proliferated to themuscles in the bladder wall but not to the fatty tissue that surroundsthe urinary bladder. Stage III: Cancer cells have proliferated to thefatty tissue surrounding the urinary bladder and to the prostate gland,vagina, or uterus, but not to the lymph nodes or other organs. Stage IV:Cancer cells have proliferated to the lymph nodes, pelvic or abdominalwall, and/or other organs. Recurrent: Cancer has recurred in the urinarybladder or in another nearby organ after having been treated.

Bladder TCC is staged according to the 1997 TNM system: Ta Non-invasivepapillary tumor; T1 Invasive but not as far as the muscular bladderlayer; T2 Invasive into the muscular layer; T3 Invasive beyond themuscle into the fat outside the bladder; and T4 Invasive intosurrounding structures like the prostate, uterus or pelvic wall.

In one embodiment, the methods described herein treat a bladder cancer.

In accordance with the invention, the humanized endoglin antibodies orfragments thereof can be administered alone or in combination withactive or inactive agents. When combinations are used, the inventioncontemplates simultaneous or sequential administration of the humanizedendoglin antibodies or antigen-binding fragments and the active orinactive agents.

Compounds of the present invention can be, as needed, administered incombination with one or more therapeutic treatments including, but notlimited to, adriamycin, cyclophosphamide, paclitaxel, pemetrexed,temozolomide, oxaliplatin, bevacizumab, erbitux, vectibix, sorafenib,sunitinib, gefitinib, erlotinib, 5-fluorouracil (5-FU) irinotecan,topotecan, leucovorin, VELCADE®, lenalidomide, thalidomide, xeloda,taxotere and many other conventional cancer therapies described herein.One would understand that the listing of therapeutic regimens listedbelow represents conventional therapies, but the present inventionencompasses other known therapeutic regimens which are not specificallydisclosed herein

As used herein, “radiation” refers to, for example, microwaves,ultraviolet (UV), infrared (IR), or alpha-, beta- or gamma-radiation.Radiation can be “focused” or locally delivered using conventionaltechniques to target radiation to the site of one or more tumors withoutradiating the entire body.

In one embodiment, the cancer is ovarian cancer and the one or moretherapeutic treatments is surgery, chemotherapy (e.g., doxorubicin,doxil, gemcitabine, Rubitecan, and platinum-based chemotherapeutics suchas cisplatin, carboplatin and oxaliplatin), melphalan, paclitaxel,topoisomerase I inhibitors such as topotecan and irinotecan,taxane-based therapy, hormones, radiation therapy, whole bodyhypothermia, isoflavone derivatives such as Phenoxodial, cytotoxicmacrolides such as Epothilones, angiogenesis inhibitors such asbevacizumab, signal transduction inhibitors such as trastuzumab, genetherapy, RNAi therapy, immunotherapy, monoclonal antibodies,phosphatidylinositol-like kinase inhibitors such as rapamycin, or anycombination thereof. In one embodiment the combination is a humanizedanti-endoglin antibody or antigen-binding fragment thereof and doxil. Inanother embodiment, the combination is a humanized anti-endoglinantibody or antigen-binding fragment thereof and topotecan. In yetanother embodiment, the combination is a humanized anti-endoglinantibody or antigen-binding fragment thereof and a VEGF receptorinhibitor. Non-limiting examples of VEGF receptor inhibitors includebevacizumab (AVASTIN®), ranibizumab (LUCENTIS®), aflibercept(VEGF-Trap), sunitinib (SUTENT®), sorafenib (NEXAVAR®), axitinib,pegaptanib and pazopanib. The combination therapy of the antibodies andantigen-binding fragments described herein with the ovarian cancertherapies may also provide for lower doses of either therapy, or both,due to a synergistic effect from the co-administration of the therapies.

In one embodiment, the cancer is renal/kidney cancer and the one or moretherapeutic treatments is surgery, chemotherapy, sunitinib, sorafenib,pazopanib, AVASTIN®, interferon-alpha, or IL-2. In one embodiment thecombination is a humanized anti-endoglin antibody or antigen-bindingfragment thereof and sorafenib. In one embodiment the combination is ahumanized anti-endoglin antibody or antigen-binding fragment thereof andsunitinib. In one embodiment the combination is a humanizedanti-endoglin antibody or antigen-binding fragment thereof and AVASTIN®.In yet another embodiment, the combination is a humanized anti-endoglinantibody or antigen-binding fragment thereof and a VEGF receptorinhibitor. Non-limiting examples of VEGF receptor inhibitors includebevacizumab (AVASTIN®), ranibizumab (LUCENTIS®), aflibercept(VEGF-Trap), sunitinib (SUTENT®), sorafenib (NEXAVAR®), axitinib,pegaptanib and pazopanib. The combination therapy of the antibodies andantigen-binding fragments described herein with the kidney cancertherapies may also provide for lower doses of either therapy, or both,due to a synergistic effect from the co-administration of the therapies.

In one embodiment, the cancer is myeloma and the one or more therapeutictreatments is surgery, radiotherapy, VELCADE®, lenalidomide, orthalidomide. In one embodiment the combination is a humanizedanti-endoglin antibody or antigen-binding fragment thereof and VELCADE®.The dosages for any of these therapies are known in the art and can beadjusted with combination therapy accordingly.

In one embodiment, the cancer is prostate cancer and the one or moretherapeutic treatments is surgery, radiotherapy (e.g., external beam orbrachytherapy), hormonal deprivation (androgen suppression), heat shockprotein 90 (HSP90) inhibitors, chemotherapy (e.g., docetaxel,platinum-based chemotherapy such as cisplatin, carboplatin, satraplatinand oxaliplatin, taxane, estramustine), prednisone or prednisolone,cholesterol-lowering drugs such as statins, leutinizinghormone-releasing hormone (LHRH) agonists, RNAi therapy, whole tumorcells genetically modified to secrete granulocyte macrophage—colonystimulating factor (GM-CSF) (also known as GVAX), or any combinationthereof. In yet another embodiment, the combination is a humanizedanti-endoglin antibody or antigen-binding fragment thereof and a VEGFreceptor inhibitor. Non-limiting examples of VEGF receptor inhibitorsinclude bevacizumab (AVASTIN®), ranibizumab (LUCENTIS®), aflibercept(VEGF-Trap), sunitinib (SUTENT®), sorafenib (NEXAVAR®), axitinib,pegaptanib and pazopanib.

In one embodiment, the cancer is lung cancer and the one or moretherapeutic treatments is surgery, radiotherapy (e.g., thoracicradiotherapy, radiation therapy with charged particles, Uracil-tegafurand Platinum-based chemotherapy (e.g., cisplatin, carboplatin,oxaliplatin, etc.) and vinorelbine, Erlotinib (TARCEVA®), Gefitinib(IRESSA®), anti-epidermal growth factor receptor antibodies (e.g.,Cetuximab), anti-vascular endothelial growth factor antibodies (e.g.,Bevacizumab), small molecule inhibitors of tyrosine kinases, directinhibitors of proteins involved in lung cancer cell proliferation,Aurora kinase inhibitors, laser-induced thermotherapy, RNAi therapy,whole tumor cells genetically modified to secrete granulocytemacrophage—colony stimulating factor (GM-CSF) (also known as GVAX), orany combination thereof. Additional therapeutic treatments include Taxoland pemetrexed. In one embodiment the combination is a humanizedanti-endoglin antibody or antigen-binding fragment thereof anderlotinib. In one embodiment the combination is a humanizedanti-endoglin antibody or antigen-binding fragment thereof andgefitinib. In one embodiment the combination is a humanizedanti-endoglin antibody or antigen-binding fragment thereof andpemetrexed. In yet another embodiment, the combination is a humanizedanti-endoglin antibody or antigen-binding fragment thereof and a VEGFreceptor inhibitor. Non-limiting examples of VEGF receptor inhibitorsinclude bevacizumab (AVASTIN®), ranibizumab (LUCENTIS®), aflibercept(VEGF-Trap), sunitinib (SUTENT®), sorafenib (NEXAVAR®), axitinib,pegaptanib and pazopanib. The dosages for any of these therapies areknown in the art and can be adjusted with combination therapyaccordingly.

In one embodiment, the cancer is breast cancer and the one or moretherapeutic treatments is surgery, monoclonal antibodies (e.g., Her-2antibodies, herceptin), adjuvant chemotherapy such as single agentchemotherapy or combination chemotherapy (e.g., anthracycline- andtaxane-based polychemotherapies, taxol, or target-specific trastuzumabwith or without endocrine manipulation with or without PMRT,vinorelbine), adriamycin, cyclophosphamide, xeloda, taxotere, selectiveestrogen receptor modulators such as Tamoxifen and Raloxifene,allosteric estrogen receptor modulators such as Trilostane, radiation(e.g., interstitial brachytherapy, Mammosite device, 3-dimensionalconformal external radiation and intraoperative radiotherapy), Aromataseinhibitors that suppress total body synthesis (e.g., anastrozole,exemestane and letrozole), RNAi therapy, intravenous analogs ofrapamycin that are immunosuppressive and anti-proliferative such asTemsirolimus (CC1779), or any combination thereof. A review of methodsfor conducting three-dimensional in vitro tissue culture models ofbreast cancer are described by Kim et al., Breast Cancer ResearchTreatment 85(3): 281-91 (2004). Other in vivo and in vitro models fortesting cancers are known and can be used to test anti-endoglinantibodies described herein. In one embodiment the combination is ahumanized anti-endoglin antibody or antigen-binding fragment thereof,taxol, and AVASTIN®. In one embodiment the combination is a humanizedanti-endoglin antibody or antigen-binding fragment thereof andadriamycin. In one embodiment the combination is a humanizedanti-endoglin antibody or antigen-binding fragment thereof and xeloda.In one embodiment the combination is a humanized anti-endoglin antibodyor antigen-binding fragment thereof and taxotere. In yet anotherembodiment, the combination is a humanized anti-endoglin antibody orantigen-binding fragment thereof and a VEGF receptor inhibitor.Non-limiting examples of VEGF receptor inhibitors include bevacizumab(AVASTIN®), ranibizumab (LUCENTIS®), aflibercept (VEGF-Trap), sunitinib(SUTENT®), sorafenib (NEXAVAR®), axitinib, pegaptanib and pazopanib. Thedosages for any of these therapies are known in the art and can beadjusted with combination therapy accordingly.

In one embodiment, the cancer is colon cancer and the one or moretherapeutic treatments is surgery, radiation therapy, and chemotherapy(e.g., 5-fluorouracil, levamisole, leucovorin or semustine (methylCCNU)), N-[2-(dimethylamino)ethyl]acridine-4-carboxamide and otherrelated carboxamide anticancer drugs; non-topoisomerase II inhibitors,irinotecan, liposomal topotecan, taxane class of anticancer agents(e.g., paclitaxel or docetaxel), a compound of the xanthenone aceticacid class (e.g., 5,6-dimethylanthenone-4-acetic acid PMAA), laminarin,site-selective cyclic AMP Analogs (e.g., 8-chloroadenosine 3′,5′-cyclicphosphate), pyranoindole inhibitors of Cox-2, carbazole inhibitors ofCox-2, tetrahydrocarbazole inhibitors of Cox-2, indene inhibitors ofCox-2, localized inhibitors of NSAIDS (e.g., anthranilic acids, aspirin(5-acetylsalicylic acid), azodisal sodium, carboheterocyclic acids,carprofen, chlorambucil, diclophenac, fenbufen, fenclofenac, fenoprofen,flufenamic acid, flurbiprofen, fluprofen, furosemide, gold sodiumthiomalate, ibuprofen, indomethacin, indoprofen, ketoprofen, lonazolac,loxoprofen, meclofenamic acid, mefanamic acid, melphalan, naproxen,penicillamine, phenylacetic acids, proprionic acids, salicylic acids,salazosulfapyridine, sulindac, tolmetin, a pyrazolone butazone propazoneNSAID, meloxicam, oxicams, piroxicam, feldene, piroxicam betacyclodextran, tenoxicam. etodolac, and oxaprozin), an inhibitor ofHER-2/neu, RNAi therapy, GM-CSF, monoclonal antibodies (e.g.,anti-Her-2/neu antibodies, anti-CEA antibodies, A33 (HB 8779), 100-210(HB 11764) and 100-310 (HB 11028)), erbitux, vectibix, hormonal therapy,pyrimidineamines, camptothecin derivatives (e.g., CPT-11), folinic acid(FA), Gemcitabine, Ara-C, platinum-based chemotherapeutics such ascisplatin, carboplatin and oxaliplatin, a cGMP-specificphosphodiesterase inhibitor, or any combination thereof. In oneembodiment the combination is a humanized anti-endoglin antibody orantigen-binding fragment thereof and a combination of 5-FU, leucovorinand oxaliplatin (FOLFOX). In one embodiment the combination is ahumanized anti-endoglin antibody or antigen-binding fragment thereof anda combination of 5-FU, irinotecan and leucovorin (IFL). In oneembodiment the combination is a humanized anti-endoglin antibody orantigen-binding fragment thereof and erbitux. In one embodiment thecombination is a humanized anti-endoglin antibody or antigen-bindingfragment thereof and a vectibix. In yet another embodiment, thecombination is a humanized anti-endoglin antibody or antigen-bindingfragment thereof and a VEGF receptor inhibitor. Non-limiting examples ofVEGF receptor inhibitors include bevacizumab (AVASTIN®), ranibizumab(LUCENTIS®), aflibercept (VEGF-Trap), sunitinib (SUTENT®), sorafenib(NEXAVAR®), axitinib, pegaptanib and pazopanib. The dosages for any ofthese therapies are known in the art and can be adjusted withcombination therapy accordingly.

In one embodiment, the cancer is pancreatic cancer and the one or moretherapeutic treatments is surgery, radiation therapy (RT), Fluorouracil(5-FU) and RT, systemic therapy, stenting, Gemcitabine (GEMZAR®),Gemcitabine and RT, Cetuximab, erlotinib (TARCEVA®), chemoradiation,bevacizumab (AVASTIN®), or any combination thereof. In yet anotherembodiment, the combination is a humanized anti-endoglin antibody orantigen-binding fragment thereof and a VEGF receptor inhibitor.Non-limiting examples of VEGF receptor inhibitors include bevacizumab(AVASTIN®), ranibizumab (LUCENTIS®), aflibercept (VEGF-Trap), sunitinib(SUTENT®), sorafenib (NEXAVAR®), axitinib, pegaptanib and pazopanib.

Patients can be assessed with respect to symptoms at one or moremultiple time points including prior to, during, and after treatmentregimens. Treatment can result in improving the subject's condition andcan be assessed by determining if one or more of the following factorshas occurred: decreased tumor size, decreased cell proliferation,decreased numbers of cells, decreased neovascularization, increasedapoptosis, or decreased survival of at least a portion of the cellscomprising the cell proliferative disorder. One or more of theseoccurrences may, in some cases, result in partial or total eliminationof the cancer and prolongation of survival of the patient.Alternatively, for terminal stage cancers, treatment may result instasis of disease, better quality of life and/or prolongation ofsurvival.

Biomarker Assessment

Certain genes can be expressed at increased or decreased levels incancers. Changes in expression levels of genes in cancers can beindicative of resistance or sensitivity to a cancer therapy ortreatment.

Provided herein is a diagnostic method for detecting the expression ofat least one gene chosen from a panel of genes whose expression has beencorrelated with sensitivity or resistance to an angiogenesis inhibitor,wherein the at least one gene is: VEGF, VEGF receptor, HIF-1α, placentalgrowth factor receptor or endoglin (CD105). The method can furtherinclude the step of comparing the level of expression of at least onegene detected in the patient sample to a level of expression of at leastone gene that has been correlated with sensitivity or resistance to theangiogenesis inhibitor. In one non-limiting embodiment, the angiogenesisinhibitor is a humanized anti-endoglin antibody. In another embodiment,the angiogenesis inhibitor is a VEGF receptor inhibitor or a VEGFinhibitor.

As used herein, the term “expression,” when used in connection withdetecting the expression of a gene, can refer to detecting transcriptionof the gene and/or to detecting translation of the gene. To detectexpression of a gene refers to the act of actively determining whether agene is expressed or not. This can include determining whether the geneexpression is upregulated as compared to a control, downregulated ascompared to a control, or unchanged as compared to a control. Therefore,the step of detecting expression does not require that expression of thegene actually is upregulated or downregulated, but rather, can alsoinclude detecting that the expression of the gene has not changed (i.e.,detecting no expression of the gene or no change in expression of thegene).

Biomarkers to be assessed in connection with the present inventioninclude VEGF receptor, placental growth factor, HIF-1α and endoglin(CD105).

For assessment of biomarker expression, patient samples containingendothelial tissue, tumor cells, or proteins or nucleic acids producedby tumor cells, can be used in methods described herein and furtherknown in the art. Briefly, the level of expression of the biomarker canbe assessed by assessing the amount (e.g., absolute amount orconcentration) of the marker in a sample, e.g., a tumor biopsy obtainedfrom a patient, or other patient sample containing material derived fromthe tumor (e.g., blood, serum, urine, or other bodily fluids orexcretions as described herein above). The cell sample can, of course,be subjected to a variety of well-known post-collection preparative andstorage techniques (e.g., nucleic acid and/or protein extraction,fixation, storage, freezing, ultrafiltration, concentration,evaporation, centrifugation, etc.) prior to assessing the amount of themarker in the sample. Likewise, tumor biopsies can also be subjected topost-collection preparative and storage techniques, e.g., fixation.

One can detect expression of biomarker proteins having at least oneportion which is displayed on the surface of cells which express it. Onecan determine whether a marker protein, or a portion thereof, is exposedon the cell surface. For example, immunological methods can be used todetect such proteins on whole cells, or well known computer-basedsequence analysis methods can be used to predict the presence of atleast one extracellular domain (i.e., including both secreted proteinsand proteins having at least one cell-surface domain). Expression of amarker protein having at least one portion which is displayed on thesurface of a cell which expresses it can be detected without necessarilylysing the tumor cell (e.g., using a labeled antibody which bindsspecifically with a cell-surface domain of the protein).

Expression of biomarkers can be assessed by any of a wide variety ofwell known methods for detecting expression of a transcribed nucleicacid or protein. Non-limiting examples of such methods include, forexample, immunological methods for detection of secreted, cell-surface,cytoplasmic, or nuclear proteins, protein purification methods, proteinfunction or activity assays, nucleic acid hybridization methods, nucleicacid reverse transcription methods, and nucleic acid amplificationmethods or any other method known in the art.

A mixture of transcribed polynucleotides obtained from the sample can becontacted with a substrate having fixed thereto a polynucleotidecomplementary to or homologous with at least a portion (e.g., at least7, 10, 15, 20, 25, 30, 40, 50, 100, 500, or more nucleotide residues) ofa biomarker nucleic acid. If polynucleotides complementary to, orhomologous with, are differentially detectable on the substrate (e.g.,detectable using different chromophores or fluorophores, or fixed todifferent selected positions), then the levels of expression of aplurality of biomarkers can be assessed simultaneously using a singlesubstrate (e.g., a “gene chip” microarray of polynucleotides fixed atselected positions). When a method of assessing biomarker expression isused which involves hybridization of one nucleic acid with another,hybridization can be performed under stringent hybridization conditions.

When a plurality of biomarkers of the invention are used in the methodsof the invention, the level of expression of each biomarker in a patientsample can be compared with the normal level of expression of each ofthe plurality of biomarkers in non-cancerous samples of the same type,either in a single reaction mixture (i.e., using reagents, such asdifferent fluorescent probes, for each biomarker) or in individualreaction mixtures corresponding to one or more of the biomarkers.

The level of expression of a biomarker in normal (i.e., non-cancerous)human tissue can be assessed in a variety of ways. This normal level ofexpression can be assessed by assessing the level of expression of thebiomarker in a portion of cells which appears to be non-cancerous, andthen comparing the normal level of expression with the level ofexpression in a portion of the tumor cells. As further informationbecomes available as a result of routine performance of the methodsdescribed herein, population-average values for normal expression of thebiomarkers can be used. Alternatively, the normal level of expression ofa biomarker can be determined by assessing expression of the biomarkerin a patient sample obtained from a non-cancer-afflicted patient, from apatient sample obtained from a patient before the suspected onset ofcancer in the patient, from archived patient samples, and the like.

An exemplary method for detecting the presence or absence of a biomarkerprotein or nucleic acid in a biological sample involves obtaining abiological sample from a test subject and contacting the biologicalsample with a compound or an agent capable of detecting the polypeptideor nucleic acid (e.g., mRNA, genomic DNA, or cDNA). The detectionmethods can, thus, be used to detect mRNA, protein, cDNA, or genomicDNA, for example, in a biological sample in vitro as well as in vivo. Invitro techniques for detection of mRNA include, for example, reversetranscriptase—polymerase chain reaction (RT-PCR; e.g., the experimentalembodiment set forth in Mullis, 1987, U.S. Pat. No. 4,683,202), Northernhybridizations and in situ hybridizations. In vitro techniques fordetection of a biomarker protein include, but are not limited to, enzymelinked immunosorbent assays (ELISAs), Western blots,immunoprecipitations and immunofluorescence. In vitro techniques fordetection of genomic DNA include, for example, Southern hybridizations.In vivo techniques for detection of mRNA include, for example,polymerase chain reaction (PCR), quantitative PCR, Northernhybridizations and in situ hybridizations. Furthermore, in vivotechniques for detection of a biomarker protein include introducing intoa subject a labeled antibody directed against the protein or fragmentthereof. For example, the antibody can be labeled with a radioactivemarker whose presence and location in a subject can be detected bystandard imaging techniques.

A general principle of such diagnostic and prognostic assays involvespreparing a sample or reaction mixture that may contain a biomarker, anda probe, under appropriate conditions and for a time sufficient to allowthe biomarker and probe to interact and bind, thus forming a complexthat can be removed and/or detected in the reaction mixture. Theseassays can be conducted in a variety of ways using a variety of methods.

It is also possible to directly detect biomarker/probe complex formationwithout further manipulation or labeling of either component (biomarkeror probe), for example by utilizing the technique of fluorescence energytransfer (i.e., FET, see for example, Lakowicz et al., U.S. Pat. No.5,631,169; and Stavrianopoulos, et al., U.S. Pat. No. 4,868,103).

In another embodiment, determination of the ability of a probe torecognize a biomarker can be accomplished without labeling either assaycomponent (probe or biomarker) by utilizing a technology such asreal-time Biomolecular Interaction Analysis (BIA; see, e.g., Sjolander,S, and Urbaniczky, C., 1991, Anal. Chem. 63:2338-2345 and Szabo et al.,1995, Curr. Opin. Struct. Biol. 5:699-705). As used herein, “BIA” or“surface plasmon resonance” refer to a technology for studyingbiospecific interactions in real time, without labeling any of theinteractants (e.g., BIAcore). Changes in the mass at the binding surface(indicative of a binding event) result in alterations of the refractiveindex of light near the surface (the optical phenomenon of surfaceplasmon resonance (SPR)), resulting in a detectable signal which can beused as an indication of real-time reactions between biologicalmolecules.

As an alternative to making determinations based on the absoluteexpression level of the biomarker, determinations can be based on thenormalized expression level of the biomarker. Expression levels arenormalized by correcting the absolute expression level of a biomarker bycomparing its expression to the expression of a gene that is not abiomarker, e.g., a housekeeping gene that is constitutively expressed.Suitable genes for normalization include housekeeping genes such as theactin gene, or epithelial cell-specific genes. This normalization allowsthe comparison of the expression level in one sample, e.g., a patientsample, to another sample, e.g., a non-tumor sample, or between samplesfrom different sources.

Alternatively, the expression level can be provided as a relativeexpression level. To determine a relative expression level of abiomarker (e.g., VEGF receptor, placental growth factor, Hif-1α andendoglin (CD105)), the level of expression of the biomarker isdetermined for 10 or more, 20 or more, 30 or more, 40 or more, or 50 ormore samples of normal versus cancer cell isolates prior to thedetermination of the expression level for the sample in question. Themean expression level of each of the genes assayed in the larger numberof samples is determined and this is used as a baseline expression levelfor the biomarker. The expression level of the biomarker determined forthe test sample (absolute level of expression) is then divided by themean expression value obtained for that biomarker. This provides arelative expression level.

In another embodiment of the present invention, a biomarker protein isdetected. One type of agent for detecting biomarker protein of theinvention is an antibody capable of binding to such a protein or afragment thereof such as, for example, a detectably labeled antibody.Antibodies can be polyclonal or monoclonal. An intact antibody, or anantigen binding fragment thereof (e.g., Fab, F(ab′)2, Fv, scFv, singlebinding chain polypeptide) can be used. The term “labeled,” with regardto the probe or antibody, is intended to encompass direct labeling ofthe probe or antibody by coupling (i.e., physically linking) adetectable substance to the probe or antibody, as well as indirectlabeling of the probe or antibody by reactivity with another reagentthat is directly labeled. Examples of indirect labeling includedetection of a primary antibody using a fluorescently labeled secondaryantibody and end-labeling of a DNA probe with biotin such that it can bedetected with fluorescently labeled streptavidin. A variety of formatscan be employed to determine whether a sample contains a protein thatbinds to a given antibody. Examples of such formats include, but are notlimited to, enzyme immunoassay (EIA), radioimmunoassay (RIA), Westernblot analysis and enzyme linked immunosorbant assay (ELISA). A skilledartisan can readily adapt known protein/antibody detection methods foruse in determining whether tumor cells express a biomarker of thepresent invention. A combination of two or more of the assays for thedetection of biomarkers (non-limiting examples include those describedabove) can also be used to assess one or more biomarkers.

Also provided herein is a method of selecting a cancer patient fortreatment with an angiogenesis inhibitor. The method comprises providinga sample of the cancer from the patient, detecting the expression of oneor more genes whose expression has been correlated with sensitivity orresistance to an angiogenesis inhibitor, comparing the level ofexpression of the gene or genes detected in the patient sample to alevel of expression of the gene or genes that have been correlated withsensitivity or resistance to the angiogenesis inhibitor. Non-limitingexamples of genes that have been correlated with sensitivity orresistance to the angiogenesis inhibitor include VEGF, VEGF receptor,HIF-1α, placental growth factor receptor, and endoglin (CD105). In afurther embodiment, a patient is selected as being predicted to benefitfrom administration of the angiogenesis inhibitor if the expression ofthe gene or genes is similar to the expression of the gene or genes thathave been correlated with sensitivity to the angiogenesis inhibitor. Inone non-limiting embodiment, the angiogenesis inhibitor for which thesubject or the subject's cancer is tested for sensitivity or resistanceis an endoglin (CD105) inhibitor (e.g., humanized anti-endoglinantibodies). In another embodiment, the angiogenesis inhibitor for whichthe subject or the subject's cancer is tested for sensitivity orresistance is a VEGF receptor inhibitor or a VEGF inhibitor.

IV. Functional Assays

Antibodies and antigen binding fragments thereof can be tested for avariety of functions using a variety of in vitro and in vivo methodsincluding, but not limited to those known in the art and those describedherein.

Methods of Assaying CD105 Signaling and Function

CD 105 (endoglin) is a member of the TGF-β receptor family that isexpressed by proliferating endothelial cells, and normal levels of CD105are needed for endothelial cell proliferation. CD105 expression isincreased by cellular hypoxia through the production ofhypoxia-inducible factor-1-α (HIF-1-α) and protects hypoxic cells fromapoptosis. CD105 acts to modulate signaling of multiple kinase receptorcomplexes of the TGF-β superfamily, including TGF-β receptors (TGF-βR),activin receptor-like kinases (ALK) and activin receptors. In theabsence of CD105, activation of TGF-β receptors results inphosphorylation of SMAD proteins that inhibit endothelial cell growth.However, activation of CD105 by TGF-β modulates SMAD proteinphosphorylation. The end result is release of the growth inhibitoryeffects of TGF-β receptor activation on endothelial cells. Prevention ofCD105 activation by anti-CD105 antibody acts synergistically with TGF-βto suppress endothelial cell growth. TGF-β can stimulate two distincttype I receptor/SMAD signaling pathways with opposite effects inendothelial cells. The TGF-β/ALK5 signaling pathway (A) leads toinhibition of cell proliferation and migration, whereas the TGF-β/ALK1pathway (B) induces endothelial cell proliferation and migration. CD105,an accessory TGF-β receptor, highly expressed during angiogenesis, isessential for ALK1 signaling. In the absence of CD105, TGF-β/ALK5signaling is predominant and maintains quiescent endothelium. High CD105expression stimulates the ALK1 pathway and indirectly inhibits ALK5signaling, thus promoting the activation state of angiogenesis.

In one non-limiting embodiment, the antibodies and antigen-bindingfragments provided herein block angiogenesis by blocking the TGF-β/ALK1signaling pathway. In another embodiment, the antibodies andantigen-binding fragments provided herein block angiogenesis bypreventing Smad1/5/8 phosphorylation and/or signaling. CD105participates in the promotion of angiogenesis through signaling of theTGF-β/ALK1, which in turn involves the decrease and/or blockage of thephosphorylation of Smad2/3 proteins. In yet another embodiment, theantibodies and antigen-binding fragments provided herein blockangiogenesis by enhancing Smad2/3 phosphorylation and/or signaling.Methods and techniques to assay the blocking or inhibitory effect of theantibodies and antigen-binding fragments provided herein on theTGF-β/ALK1 signaling pathway and/or the phosphorylation of Smad1/5include, but are not limited to, known molecular techniques. By way ofexample, western blotting with antibodies specific to any of theproteins in the TGF-β/ALK5 or TGF-β/ALK1 pathways can be used todetermine the inhibitory and/or stimulatory effect of the antibodies andantigen-binding fragments disclosed herein on the TGF-β/ALK5 orTGF-β/ALK1 pathways. Similarly, detection of mRNA or regulation of themRNA for the proteins involved in the TGF-β/ALK5 or TGF-β/ALK1 pathwayscan be used to assay the inhibitory and/or stimulatory effect of theantibodies and antigen-binding fragments disclosed herein. Additionalmethods for the assaying cell signaling for the TGF-β/ALK5 or TGF-β/ALK1pathways are known in the art and are contemplated herein.

In one non-limiting embodiment, the antibodies can be assessed withrespect to inhibiting angiogenesis and endothelial cell proliferation.Binding of anti-endoglin antibodies to HUVECs does not preventsubsequent binding of TGF-β to HUVECs. Thus, direct suppression of theendothelial cell growth by anti-endoglin antibodies represents one ofthe underlying mechanisms by which anti-angiogenic and tumor-suppressiveeffects are observed in vivo. In another embodiment, the antibodies canbe assessed with respect to blocking angiogenesis by preventingSmad1/5/8 phosphorylation and/or signaling. CD105 participates in thepromotion of angiogenesis through signaling of the TGF-β/ALK1, which inturn involves the decrease and/or blockage of the phosphorylation ofSmad2/3 proteins. In yet another embodiment, the antibodies can beassessed with respect to blocking angiogenesis by enhancing Smad2/3phosphorylation and/or signaling.

Methods and techniques to assay the blocking or inhibitory effect of theantibodies provided herein on the TGF-β/ALK1 signaling pathway and/orthe phosphorylation of Smad1/5 include, but are not limited to, knownmolecular techniques. By way of example, western blotting withantibodies specific to any of the proteins in the TGF-β/ALK5 orTGF-β/ALK1 pathways can be used to determine the inhibitory and/orstimulatory effect of the anti-endoglin antibodies disclosed herein onthe TGF-β/ALK5 or TGF-β/ALK1 pathways. Similarly, detection of mRNA orregulation of the mRNA for the proteins involved in the TGF-β/ALK5 orTGF-β/ALK1 pathways can be used to assay the inhibitory and/orstimulatory effect of the antibodies disclosed herein. Additionalmethods for the assaying cell signaling for the TGF-β/ALK5 or TGF-β/ALK1pathways are known in the art and are contemplated herein.

Activity of the anti-endoglin antibodies disclosed herein can beassessed using art recognized assays by, for example, binding assayssuch ELISAs, competitive ELISAs, surface plasmon resonance, and effecton HUVEC cells as described in more detail below.

Methods of Assaying Cell Adhesion

Cell adhesion can be measured by methods known to those of skill in theart. Assays have been described previously, e.g. by Lebrin, et al., J.Clin. Invest 1997, 99:1390-1398. Briefly, cells can be allowed to adhereto substrate (i.e., an ECM component) on coated wells. Non-attachedcells are removed by washing, and non-specific binding sites are blockedby incubation with BSA. The attached cells are stained with crystalviolet, and cell adhesion is quantified by measuring the optical densityof eluted crystal violet from attached cells at a wavelength of 600 nm.

Methods of Assaying Cell Migration

Assays for cell migration have been described in the literature, e.g.,by Brooks, et al., J. Clin. Invest 1997, 99:1390-1398 and methods formeasuring cell migration are known to those of skill in the art. In onemethod for measuring cell migration described herein, membranes fromtranswell migration chambers are coated with substrate, the transwellswashed, and non-specific binding sites blocked with BSA. Tumor cellsfrom sub-confluent cultures are harvested, washed, and resuspended inmigration buffer in the presence or absence of assay antibodies. Afterthe tumor cells are allowed to migrate to the underside of the coatedtranswell membranes, the cells remaining on the top-side of the membraneare removed and cells that migrate to the under-side are stained withcrystal violet. Cell migration is then quantified by direct cell countsper microscopic field.

SCID/Nude Mice

One method for assaying tumor growth makes use of SCID mouse, asfollows: subconfluent human M21 melanoma cells are harvested, washed,and resuspended in sterile PBS (20×10⁶ per mL). SCID mice are injectedsubcutaneously with 100 μL of M21 human melanoma cell (2×10⁶)suspension. Three days after tumor cell injection, mice are eitheruntreated or treated intravenously or intraperitoneally (for example,100 μg/mouse) with one or more control or test compositions. The miceare treated daily for 24 days. Tumor size is measured with calipers andthe volume estimated using the formula V=(L×W²)/2, where V is equal tothe volume, L is equal to the length, and W is equal to the width.

One method for assaying tumor growth makes use of nude mouse, asfollows: MDA-MB-435 tumor cells (0.4×10⁶ cells/mouse) in 50 μl PBS areorthotopically implanted in the mammary fat pad of female nude mice(five to six weeks old). When tumors reached a mean volume ofapproximately 50-80 mm³, mice are randomized (at least 10/group) andintravenous or intraperitoneal treatment with one or more antibodies at1 μg (0.05 mg/kg) per dose, 10 μg (0.5 mg/kg), 100 μg (5 mg/kg) or 200μg (10 mg/kg), or 100 μg control antibody in 100 μl PBS, or vehicle PBS100 μl twice per week is initiated; in some studies, an untreated groupcan also be evaluated. Tumor size is measured with calipers and thevolume estimated using the formula V=(L×W²)/2, where V is equal to thevolume, L is equal to the length, and W is equal to the width.

BALB/c Syngeneic Mouse Models

Alternatively, BALB/c syngeneic mouse models can also be utilized toassess tumor growth and inhibition thereof by the antibodies ordescribed herein as exemplified by, for example, Tsujie et al., Int. J.Oncology, 29: 1087-1094 (2006).

Chimeric Mice

Another assay measures angiogenesis in a chimeric mouse:human mousemodel and is referred to as the chimeric mouse assay. The assay has beendescribed in detail by others, and further has been described herein tomeasure angiogenesis, neovascularization, and regression of tumortissues. See Yan, et al. (1993) J. Clin. Invest. 91:986-996.

The chimeric mouse assay is a useful assay model for in vivoangiogenesis because the transplanted skin grafts closely resemblenormal human skin histologically and neovascularization of whole tissueis occurring wherein actual human blood vessels are growing from thegrafted human skin into the human tumor tissue on the surface of thegrafted human skin. The origin of the neovascularization into the humangraft can be demonstrated by immunohistochemical staining of theneovasculature with human-specific endothelial cell markers.

The chimeric mouse assay demonstrates regression of neovascularizationbased on both the amount and extent of regression of new vessel growth.Furthermore, it is easy to monitor effects on the growth of any tissuetransplanted upon the grafted skin, such as a tumor tissue. Finally, theassay is useful because there is an internal control for toxicity in theassay system. The chimeric mouse is exposed to any test reagent, andtherefore the health of the mouse is an indication of toxicity. Otheranimal models described herein and known in the art can also be utilizedin the methods described herein.

Rabbit Eye Assay

Another measure of angiogenesis is an in vivo rabbit eye model and isreferred to as the rabbit eye assay. The rabbit eye assay has beendescribed in detail by others, and has been used to measure bothangiogenesis and neovascularization in the presence of angiogenicinhibitors as exemplified by D'Amato et al. (1994) Proc. Natl. Acad.Sci. USA, 91(9): 4082-4085.

The rabbit eye assay is a recognized assay model for in vivoangiogenesis because the neovascularization process, exemplified byrabbit blood vessels growing from the rim of the cornea into the cornea,is easily visualized through the naturally transparent cornea of theeye. Additionally, both the extent and the amount of stimulation orinhibition of neovascularization or regression of neovascularization caneasily be monitored over time.

Finally, the rabbit is exposed to any test reagent, and therefore thehealth of the rabbit is an indication of toxicity of the test reagent.

Briefly, chicken chorioallantoic membrane (CAM) assays are performed andthe effects on the developing vasculature are recorded at 48 hours afterimplantation of a 0.5% carboxymethylcellulose pellet containing one ormore control or test compounds. Corneal neovascularization is induced byan implanted pellet of poly(hydroxyethyl methacrylate) (Hydron;Interferon Sciences, New Brunswick, N.J.) containing 650 ng of thepotent angiogenic protein basic fibroblast growth factor (bFGF) bound tosucralfate (sucrose aluminum sulfate; Bukh Meditec, Copenhagen). Theaddition of sucralfate to the pellet protects the bFGF from degradationand provides for its slow release, thus producing consistent aggressiveangiogenesis that is more pronounced than that induced by bFGF/Hydronalone. Release of bFGF from pellets containing sucralfate/Hydron can bedetected in vitro for up to 4 days after the pellets are formed comparedto just 1 day for pellets with Hydron alone. Pellets are made by mixing110 μl of saline containing 12 μg of recombinant bFGF (Takeda, Osaka)with 40 mg of sucralfate; this suspension is added to 80 μl of 12%(wt/vol) Hydron in ethanol. Aliquots (10 μl) of this mixture are thenpipetted onto Teflon pegs and allowed to dry producing approximately 17pellets.

A pellet is implanted into corneal micropockets of each eye of ananesthetized female New Zealand White rabbit, 2 mm from the limbus,followed by a single topical application of erythromycin ointment on thesurface of the cornea. Histologic examination on consecutive daysdemonstrates progressive blood vessel growth into the cornea toward thepellet with only rare inflammatory cells seen. This angiogenic responseis not altered by severe immune suppression with total body irradiation,and pellets with sucralfate alone do not induce angiogenesis. Newvessels are primarily induced by the bFGF rather than by inflammation.The animals are fed daily from 2 days after implantation by gastriclavage with one or more compounds suspended in 0.5%carboxymethylcellulose or vehicle alone. Immunosuppressed animalsreceive total body radiation of 6 Gy for 6 minutes immediately prior toimplantation of the pellets. This dose of radiation results in a markedleukocytopenia with >80% reduction in the leukocyte count by day 2and >90% reduction by day 3, results that are consistent with previousreports.

Animals are examined with a slit lamp every other day in a masked mannerby the same corneal specialist (M.S.L.). The area of cornealneovascularization is determined by measuring with a reticule the vessellength (L) from the limbus and the number of clock hours (C) of limbusinvolved. A formula is used to determine the area of a circular bandsegment: C/12×3.1416[r²−(r−L)²], where r=6 mm, the measured radius ofthe rabbit cornea. The uniform contiguous band of neovascularizationadjacent to the pellet is measured, thus, the total inhibition ofneovascularization can be assessed.

Mouse Matrigel Pug Angiogenesis Assays

To confirm the effects of a composition on angiogenesis, a mouseMatrigel plug angiogenesis assay can be used. Various growth factors(e.g., IGF-1, bFGF or VEGF) (250 ng) and Heparin (0.0025 units per/mL)are mixed with growth factor reduced Matrigel as previously described(Montesano, et al., J. Cell Biol. 1983, 97:1648-1652; Stefansson, etal., J. Biol. Chem. 2000, 276:8135-8141). Compositions described hereinor control antibodies can be included in the Matrigel preparationsutilizing one or more dosage groups of animals. In control experiments,Matrigel is prepared in the absence of growth factors. Mice are injectedsubcutaneously with 0.5 mL of the Matrigel preparation and allowed toincubate for one week. Following the incubation period, the mice aresacrificed and the polymerized Matrigel plugs surgically removed.Angiogenesis within the Matrigel plugs is quantified by two establishedmethods, including immunohistochemical analysis and hemoglobin content(Furstenberger, et al., Lancet. 2002, 3:298-302; Volpert, et al., CancerCell 2002, 2(6):473-83; and Su, et al., Cancer Res. 2003, 63:3585-3592).For immunohistochemical analysis, the Matrigel plugs are embedded inOCT, snap frozen and 4 μm sections prepared. Frozen sections are fixedin methanol/acetone (1:1). Frozen sections are stained with polyclonalantibody directed to CD31. Angiogenesis is quantified by microvasculardensity counts within 20 high powered (200×) microscopic fields.

Hemoglobin content can be quantified as described previously (Schnaper,et al., J. Cell Physiol. 1993, 256:235-246; Montesano, et al., J. CellBiol. 1983, 97:1648-1652; Stefansson, et al., J. Biol. Chem. 2000,276:8135-8141; and Gigli, et al., J. Immunol. 1986, 100:1154-1164). TheMatrigel implants are snap frozen on dry ice and lyophilized overnight.The dried implants are resuspended in 0.4 mL of 1.0% saponin(Calbiochem) for one hour, and disrupted by vigorous pipetting. Thepreparations are centrifuged at 14,000×g for 15 minutes to remove anyparticulates. The concentration of hemoglobin in the supernatant is thendetermined directly by measuring the absorbency at 405 nm and comparedto a standard concentration of purified hemoglobin.

Methods of Assaying Tumor Growth

Tumor growth can be assayed by methods known to those of skill in theart, e.g., the SCID mouse model, the nude mouse model, and BALB/c micewith syngeneic tumors. SCID mouse models for tumor growth are carriedout as follows: subconfluent human M21 melanoma cells (or any desiredtumor cell type) are harvested, washed, and resuspended in sterile PBS(20×106 per mL). SCID mice are injected subcutaneously with 100 μL ofM21 human melanoma cell (2×10⁶) suspension. Three days after tumor cellinjection, mice are either untreated or treated intraperitoneally withan antagonist in the desired dose ranges. The mice are treated daily for24 days. Tumor size is measured with calipers and the volume estimatedusing the formula V=(L×W²)/2, where V is equal to the volume, L is equalto the length, and W is equal to the width.

Alternatively, nude mouse models, SCID mouse models and/or BALB/csyngeneic mouse models can also be utilized to assess tumor growth andinhibition thereof by the humanized anti-endoglin antibodies orantigen-binding fragments described herein. (Tsujie et al., Int. J.Oncology, 29: 1087-1094 (2006)).

Methods of Assaying Cell Proliferation

Cell proliferation can be assayed by methods known to those of skill inthe art. As described herein, subconfluent human endothelial cells(HUVECs) can be resuspended in proliferation buffer containing low(5.0%) serum in the presence or absence of CM (25 μL) from ECV or ECVLcells, and endothelial cells allowed to proliferate for 24 hours.Proliferation can be quantified by measuring mitochondrial dehydrogenaseactivity using a commercially available WST-1 assay kit (Chemicon).Also, as described herein, proliferation can be quantified by measuring³H incorporation using standard methods. (She et al., Int. J. Cancer,108: 251-257 (2004)).

Other methods of assessing cell proliferation are known in the art andare contemplated herein. Further non-limiting examples are described inmore detail in the examples.

Methods of Inducing CDC, ADCC and Opsonization

Various therapies have been directed to augmenting the body's naturalimmune response to transformed cells. Conventional effector methodsinclude complement dependent cytolysis (“CDC”), antibody dependentcellular cytotoxicity (“ADCC”) and phagocytosis (clearance byreticuloendothelial system after the target cell is coated withimmunoglobulin). It is known that in the presence of antibodies, certaineffector cells, such as lymphoid cells having surface bound receptorsfor the Fc regions of antibodies, mediate an antibody dependent cellularcytoxicity (“ADCC”) reaction against target cells. By means of ADCC,these effector cells exert cytolytic activity against such target cells.

Two types of ADCC reactions have been demonstrated in vitro. Inclassical ADCC reactions, effector cells attach to antibody-coatedtarget cells and subsequently cause cytolysis of the target cells (A. H.Greenberg et al., “Characteristics Of The Effector Cells MediatingCytotoxicity Against Antibody-Coated Target Cells.” I., Immunology, 21,p. 719 (1975)). This attachment between effector and target cell resultsfrom the interaction of the Fc region of the antibody coating the targetcell and the Fc receptor of the effector cell. One disadvantage of thistype of ADCC reaction is that it may be hampered by circulatingantigen-antibody complexes, often associated with various diseases,which compete with the target-cell bound antibody for the Fc receptorsof the effector cells (I. C. M. MacLennan, “Competition For ReceptorsFor Immunoglobulin On Cytotoxic Lymphocytes,” Clin. Exp. Immunol., 10,p. 275 (1972)). Due to this drawback of classical ADCC, a second type ofADCC reaction—antibody-directed ADCC—has been proposed. Inantibody-directed ADCC, the target-specific antibody is first attachedto the effector cell and the resulting complex is then “directed,” viathe antibody, to its specific antigen on the target cell surface.Advantageously, antibody-directed ADCC may not be affected by thepresence of antigen-antibody complexes circulating in the host system.The interaction between antibodies and effector cells via Fc region/Fcreceptor attachment is normally weak. And, in some instances, antibodiesdo not remain associated with effector cells for a period of timesufficient to permit lysis of target cells. In view of this potentialproblem, antibodies have been attached to the effector cells usingpre-treatment with polyethylene glycol and a mixture of phthalate oils(J. F. Jones and D. M. Segal, “Antibody-Dependent Cell MediatedCytolysis (ADCC) With Antibody-Coated Effectors: New Methods ForEnhancing Antibody Binding And Cytolysis,” J. Immunol., 125, pp. 926-33(1980)). The applicability of this method for in vivo treatments,however, may be diminished by the toxic effects that any polyethyleneglycol and phthalate oil residues on the antibody-effector cell complexmay have on the body.

Alternatively, a method has been proposed for enhancingantibody-directed ADCC by adjuvant chemotherapy with cytotoxic drugs (I.R. Mackay et al., “Effect On Natural Killer And Antibody-DependentCellular Cytotoxicity Of Adjuvant Cytotoxic Chemotherapy IncludingMelphalan In Breast Cancer,” Cancer Immunol. Immunother., 16, pp. 98-100(1983)). Assays for testing for ADCC are well-known in the art, such asfor example, U.S. Pat. No. 5,756,097.

Accordingly, the present invention provides antibodies (e.g., humanizedanti-endoglin antibodies) that can bind to cells having a role inneovascularization or angiogenesis of that can enhance phagocytosis andkilling of the cells and thereby enhance protection in vivo. Alsoprovided are other antibodies and functional fragments thereof thatimmunoreact, specifically bind to, or preferentially bind to a bindingsite or epitope to which such antibodies can bind and which have thesame effect.

The antibodies of the invention can also be opsonic, or exhibit opsonicactivity, for cells having a role in neovascularization or angiogenesis(e.g., endothelial cells). As those in the art recognize, “opsonicactivity” refers to the ability of an opsonin (generally either anantibody or the serum factor C3b) to bind to an antigen or cell receptorto promote attachment of the antigen or cell receptor to a phagocyte andthereby enhance phagocytosis. Certain cells become extremely attractiveto phagocytes such as neutrophils and macrophages when coated with anopsonic antibody and their rate of clearance from the bloodstream isstrikingly enhanced. Opsonic activity may be measured in anyconventional manner as described, for example, in U.S. Pat. No.6,610,293.

In another non-limiting embodiment, a patient having a neovasculardisorder or an angiogenesis dependent disorder sheds antigens/peptides(e.g., endoglin) from the angiogenesis. These antigens/peptides can be“tumor associated antigens.” Such patients can be systemicallyadministered an antibody to the antigen/peptide (e.g., endoglin) and caninitiate any of the pathways described herein to induce CDC, ADCC,opsonization, or any other form of cell-mediated killing.

V. Packages and Kits

In still further embodiments, the present application concerns kits foruse with the compounds described above. Humanized antibodies orantigen-binding fragments that bind endoglin can be provided in a kit.The kits will thus comprise, in suitable container means, a compositioncomprising an antibody or antigen-binding fragment thereof that bindsendoglin. The kit may comprise an antibody or antigen-binding fragmentthereof that binds endoglin in suitable container means.

The container means of the kits will generally include at least onevial, test tube, flask, bottle, syringe and/or other container means,into which the at least one polypeptide can be placed, and/orpreferably, suitably aliquoted. The kits can include a means forcontaining at least one fusion protein, detectable moiety, reportermolecule, and/or any other reagent containers in close confinement forcommercial sale. Such containers may include injection and/orblow-molded plastic containers into which the desired vials areretained. Kits can also include printed material for use of thematerials in the kit.

Packages and kits can additionally include a buffering agent, apreservative and/or a stabilizing agent in a pharmaceutical formulation.Each component of the kit can be enclosed within an individual containerand all of the various containers can be within a single package.Invention kits can be designed for cold storage or room temperaturestorage.

Additionally, the preparations can contain stabilizers to increase theshelf-life of the kits and include, for example, bovine serum albumin(BSA). Where the compositions are lyophilized, the kit can containfurther preparations of solutions to reconstitute the lyophilizedpreparations. Acceptable reconstitution solutions are well known in theart and include, for example, pharmaceutically acceptable phosphatebuffered saline (PBS).

Additionally, the packages or kits provided herein can further includeany of the other moieties provided herein such as, for example, one ormore reporter molecules and/or one or more detectable moieties/agents.

Packages and kits can further include one or more components for anassay, such as, for example, an ELISA assay. Samples to be tested inthis application include, for example, blood, plasma, and tissuesections and secretions, urine, lymph, and products thereof. Packagesand kits can further include one or more components for collection of asample (e.g., a syringe, a cup, a swab, etc.).

Packages and kits can further include a label specifying, for example, aproduct description, mode of administration and/or indication oftreatment. Packages provided herein can include any of the compositionsas described herein. The package can further include a label fortreating an ocular diseases characterized byangiogenesis/neovascularization (e.g., macular degeneration, CNV,diabetic retinopathy), diabetic nephropathy, a chronic inflammatorydisease (e.g., IBD), rheumatoid arthritis, osteoarthritis, a forms ofcancer and their metastases.

The term “packaging material” refers to a physical structure housing thecomponents of the kit. The packaging material can maintain thecomponents sterilely and can be made of material commonly used for suchpurposes (e.g., paper, corrugated fiber, glass, plastic, foil, ampules,etc.). The label or packaging insert can include appropriate writteninstructions. Kits, therefore, can additionally include labels orinstructions for using the kit components in any method of theinvention. A kit can include a compound in a pack, or dispenser togetherwith instructions for administering the compound in a method describedherein.

The invention further provides kits which utilize the diagnostic methodsand assays described herein. In some embodiments, a kit according to theinvention comprises reagents for the detection of a gene or genes whoseexpression levels have been correlated with sensitivity or resistance toan angiogenesis inhibitor in a sample of cancer cells from a patient. Insome embodiments, the gene or genes are selected from VEGF, VEGFreceptor, HIF-1α, placental growth factor receptor, and CD105. In someembodiments, the kit comprises VEGF. In some embodiments, the kitcomprises VEGF receptor. In some embodiments, the kit comprises HIF-1α.In some embodiments, the kit comprises placental growth factor receptor.In some embodiments, the kit comprises CD105. In some embodiments, thekit comprises at least two of VEGF, VEGF receptor, HIF-1α, placentalgrowth factor receptor and CD105. In some embodiments, the kit comprisesat least two genes that have been correlated with sensitivity to anangiogenesis inhibitor. In some embodiments, the kit comprises at leasttwo genes that have been correlated with resistance to an angiogenesisinhibitor. In some embodiments, the kit comprises at least one gene thathas been correlated with sensitivity to an angiogenesis inhibitor andone gene that has been correlated with resistance to an angiogenesisinhibitor.

In still further embodiments, a kit according to the invention comprisesreagents for the detection of VEGF, VEGF receptor, HIF-1α, placentalgrowth factor receptor, and CD105 expression levels in a sample of tumorcells from a patient to be treated; and a dose or doses an inhibitor,including but not limited to humanized anti-endoglin antibodies orantigen-binding fragments described herein, in a variety of dosageforms, such as capsules, caplets, gel caps, powders for suspension, etc.It is further contemplated within the invention that kit comprisingreagents for the detection of VEGF, VEGF receptor, HIF-1α, placentalgrowth factor receptor, and CD105 expression levels in a sample of tumorcells from a patient to be treated will further comprise any of theaforementioned embodiments of the kits for co-administration of at leastone additional angiogenesis inhibitor.

Instructions can include instructions for practicing any of the methodsdescribed herein including treatment methods. Instructions canadditionally include indications of a satisfactory clinical endpoint orany adverse symptoms that may occur, or additional information requiredby regulatory agencies such as the Food and Drug Administration for useon a human subject.

The instructions may be on “printed matter,” e.g., on paper or cardboardwithin or affixed to the kit, or on a label affixed to the kit orpackaging material, or attached to a vial or tube containing a componentof the kit. Instructions may additionally be included on a computerreadable medium, such as a disk (floppy diskette or hard disk), opticalCD such as CD- or DVD-ROM/RAM, magnetic tape, electrical storage mediasuch as RAM and ROM, IC tip and hybrids of these such asmagnetic/optical storage media.

The embodiments of the compounds and methods of the present applicationare intended to be illustrative and not limiting. Modifications andvariations can be made by persons skilled in the art in light of theabove teachings specifically those that may pertain to alterations inthe antibodies or antigen-binding fragments which bind endoglinsurrounding the described modifications while maintaining near nativefunctionally with respect to binding of endoglin. Therefore, it shouldbe understood that changes may be made in the particular embodimentsdisclosed which are within the scope of what is described.

EXAMPLES

The application may be better understood by reference to the followingnon-limiting examples, which are provided as exemplary embodiments ofthe application. The following examples are presented in order to morefully illustrate embodiments of the invention and should in no way beconstrued, however, as limiting the broad scope of the application.While certain embodiments of the present application have been shown anddescribed herein, it will be obvious that such embodiments are providedby way of example only. Numerous variations, changes, and substitutionsmay occur to those skilled in the art without departing from theinvention; it should be understood that various alternatives to theembodiments described herein may be employed in practicing the methodsdescribed herein.

Example 1 Generation and Binding of Anti-CD105 Humanized andHumanized/Deimmunized Antibodies

Construction, Expression and Purification of Antibodies

All humanized and humanized/deimmunized VH and VK region genes weresynthesized using a series of overlapping oligonucleotides that wereannealed, ligated and PCR amplified to give full length synthetic Vregions. The assembled variants were then cloned directly into AntitopeLtd.'s pANT expression vector system for IgG1 heavy chains and kappalight chains.

All combinations of humanized heavy and light chains (i.e., a total of 4pairings) and combinations of humanized/deimmunized heavy and lightchains (i.e., a total of 24 pairings) were stably transfected into NS0cells via electroporation and selected using 200 nM methotrexate (SigmaCat. No. M8407). Methotrexate-resistant colonies for each construct weretested for IgG expression levels using an IgG1 ELISA. The bestexpressing lines were selected and frozen under liquid nitrogen.Successful transfection and clone selection was achieved for allvariants and expression levels of humanized and humanized/deimmunizedantibody variants in saturated static cultures are shown in Table 1.

Twenty-four IgG1 variants were therefore purified from NS0 cell culturesupernatants on a Protein A sepharose column (GE Healthcare Cat. No.110034-93) and quantified by OD_(280nm) using an extinction coefficient,Ec_((0.1%))=1.62, based on the predicted amino acid sequence.Approximately 500 μg of each antibody variant was purified and leadvariants were analyzed by reducing SDS-PAGE. Briefly, Coomassie bluestained reducing SDS-PAGE gel of lead antibody variants. 1 μg of eachsample was loaded on a NuPage 4-12% Bis-Tris gel (Invitrogen Cat. No.NP0322BOX) and run at 200 V for 30 minutes. Marker was Bio-Rad PrecisionPlus (Cat. No. 161-073). Bands corresponding to the predicted sizes ofthe heavy and light chains were observed with no evidence of anycontamination in any lane (data not shown).

ELISA Methodology

An ELISA was used to assay binding of humanized andhumanized/deimmunized anti-endoglin antibodies to endoglin. Briefly, anELISA was performed according to the following steps:

-   -   1. Coat a Nunc Maxisorp plate with MAB9811-01 (polyclonal        anti-endoglin antibody) at 1500 ng/ml in PBS, 100 μl/well. Cover        the plate with a sealer and incubate overnight (16-24 hours) at        4° C.    -   2. Wash the plate 2× with −200 μl of PBS (without Tween).    -   3. Add 200 μl/well of BSA blocking solution (1% BSA) and        incubate 60 minutes at room temperature.    -   4. Wash the plate 3× with PBS containing Tween (PBS-T) using the        BioTek plate washer.    -   5. Add 100 μl/well of CD105 (R&D Systems Cat 1097-EN) at 100        ng/ml in PBS-T with 0.1% BSA and incubate 60 minutes at room        temperature.    -   6. Wash the plate 3× with PBS-T using the BioTek plate washer.    -   7. In test wells: add 100 μl/well of anti-endoglin antibodies at        20, 10, 4, 2, 1, 0.5 and 0.2 ng/ml (diluted in PBS-T with 0.1%        BSA) and incubate 60 minutes at room temperature. In negative        control wells: add 100 μl/well of isotype matched control        antibody.    -   8. Wash the plate 3× with PBS-T using the BioTek plate washer.    -   9. Add 100 μl/well of Goat anti-Human IgG conjugated to HRP        (Jackson Immunoresearch), diluted 1:10000 in PBS-T with 0.1% BSA        to all wells; incubate 30-60 minutes at room temperature.    -   10. Wash the plate 5× with PBS-T using the BioTek plate washer.    -   11. Add 100 μl/well of TMB substrate solution and incubate        uncovered in the dark for 15 minutes.    -   12. Stop the reaction by addition of 100 μl/well of TMB Stop        Solution.

Samples are run in triplicate and the optical density is read toconstruct a standard curve and determine the binding constant.Statistical analysis is conducted using the Student's t-test or anotherstandard test.

Competition ELISA

Antibodies were tested in a competition ELISA for binding to CD105against biotinylated chimeric anti-CD105. Briefly, chimeric anti-CD105was biotinylated using a micro-biotinylation kit (Sigma, Catalog No.BTAG-1KT) following the manufacturer's instructions. Nunc ImmunoMaxiSorp 96-well flat-bottom microtiter plates were coated with mouseanti-human CD105 (Southern Biotechnologies, Catalog No. 9811-01) at 1.5μg/mL in phosphate buffered saline (PBS) overnight at 4° C. Thefollowing day, 100 ng/ml human CD105 (R&D Systems, Catalog No. 1097-EN)in PBS/2% BSA was added to the pre-coated plate and incubated at roomtemperature for 1 hour. Varying concentrations of either chimeric,humanized or humanized/deimmunized anti-CD105 antibodies (4 μg/mL to0.0018 pg/mL in three-fold dilutions) were mixed with a fixedconcentration of biotinylated chimeric anti-CD105 antibody (6.25 ng/ml)and added to the plate. Binding of the biotinylated chimeric antibodywas detected via streptavidin-HRP (Sigma, Catalog No. S5512) and TMBsubstrate (Sigma, Catalog No. T0440). OD450 nm values were measured on aDynex MRX TCII plate reader. The results of the competition analysis areillustrated in FIGS. 7 and 8. Curves were fitted through the straightline portion of each of the plots of absorbance against the log sampleconcentration and the equations of the lines were used to calculate theconcentrations of humanized or humanized/deimmunized antibody requiredto inhibit biotinylated chimeric antibody binding to CD105 by 50%(IC50). To allow for comparisons within and between experiments, IC₅₀values of humanized or humanized/deimmunized variants were normalizedagainst the reference antibody that was included on each plate to give avalue for the fold difference. IC50 values are relative to chimericanti-CD105 and are representative of three experiments. Summary ELISAdata are presented in Table 1 and include antibody expression levels(μg/ml) as assayed in saturated static cultures.

TABLE 1 Characteristics of humanized and humanized/deimmunized antibodyvariants. IC50 values are relative to chimeric anti-endoglin antibodyand are representative of three experiments. Antibody expression levels(μg/ml) were assayed in saturated static cultures. The level ofdeimmunization is represented by an arbitrary scale based upon thelocation in the epitopes of the mutations. Expression Levels Level ofConstruct Relative IC50 (μg/ml) Deimmunization VK1VH1 1.51 10.2 n/aVK1VH2 1.15 12.9 n/a VK2VH1 0.93 11.1 n/a VK2VH2 1.19 15.8 n/a VK2AAVH1A0.79 10.8 ++++ VK2AAVH1A2 0.99 6.6 ++++++ VK2AAVH1Q 0.76 7.5 +++++VK2AAVH1R 0.61 10.0 +++++ VK2AAVH1S 1.27 9.7 ++++ VK2ASVH1A 1.41 6.6 +++VK2ASVH1A2 0.85 5.9 +++++ VK2ASVH1Q 1.04 8.7 ++++ VK2ASVH1R 1.02 7.9++++ VK2ASVH1S 1.31 8.8 +++ VK2SAVH1A 0.49 7.5 +++ VK2SAVH1A2 0.84 10.3+++++ VK2SAVH1Q 0.87 11.5 ++++ VK2SAVH1R 0.77 8.8 ++++ VK2SAVH1S 0.9634.6 +++ VK2SSVH1A 1.06 9.7 ++ VK2SSVH1A2 1.03 17.4 ++++ VK2SSVH1Q 1.2114.7 +++ VK2SSVH1R 0.62 13.7 +++ VK2SSVH1S 1.21 16.2 +++ VK1AAVH1A 2.526.9 ++++ VK1AAVH1A2 1.12 13.5 ++++++ VK1AAVH1Q 1.30 7.6 +++++ VK1AAVH1R1.05 11.5 +++++

Example 2 BIAcore (Surface Plasmon Resonance: SPR) Analysis of Humanizedand Humanized/Deimmunized Anti-Endoglin Antibody Binding

Affinity of antibodies can be assessed using, for example, BIAcoreanalysis using standard protocols. Briefly, protein A is chemicallycoupled to a BIAcore CM5 chip, with the amount of protein A immobilizedcorresponding to ˜2000 RU. Subsequent steps are performed in a runningbuffer of 10 mM HEPES, 150 mM NaCL, 3 mM EDTA, 0.05% TWEEN, pH=7.4, at25 degrees Celsius using a 10 Hz data collection rate. Anti-endoglinantibody (10 nM) is captured at a 10 uL/min flow rate by the immobilizedprotein A on the BIAcore chip: typically, capture times of 20, 40 and 80seconds allow the capture of antibody densities corresponding to 130 RU,330RU and 570 RU, respectively. Start-up cycles are performed usingrunning buffer at a flow rate of 40 uL/min, a contact time of 90 secondsand a dissociation time of 90 seconds. Sample cycles are performed usingrecombinant endoglin at concentrations ranging from 0 to 40 nM. Endoglinis passed over the BIAcore chip containing captured antibody at a flowrate of 40 uL/min with a contact time of 525 seconds and dissociationtime of 2500 seconds. Eight sample cycles are typically performed ateach antibody capture density Regeneration of the chip is accomplishedusing 10 mM glycine pH=1.7. Data analysis is performed using BIAcoreT100 Evaluation Software v1.1 Signals generated using BIAcore chips withdifferent captured antibody densities are compared and data generated inthe absence of recombinant endoglin are used to adjust for theintraassay blank signal. For fitting of the data, the R_(max) is allowedto float to account for variation in capture levels of each antibody ineach cycle. Data from each capture density is fitted simultaneouslyduring analysis of each antibody. BIAcore data are presented in Table 2for chimeric, humanized and humanized/deimmunized anti-endoglinantibodies, including k_(a) (1/Ms), k_(d) (1/s), K_(D) (M) and Chi²(RU²).

TABLE 2 BIAcore binding data for chimeric anti-endoglin antibody,humanized anti-endoglin antibody VK1VH1 and humanized/deimmunizedanti-endoglin antibodies VK1AAVH1R, VK1AAVH1Q and VK1AAVKVH1A2.Anti-endoglin k_(a) k_(d) K_(D) Chi² Antibody (×10⁴) (×10⁻⁵) (×10⁻¹⁰)(×10⁻²) VK1AAVH1R 6.40 3.41 5.33 6.84 VK1VH1 4.19 3.46 8.25 5.53Chimeric 5.47 3.28 6.00 6.78 VK1AAVH1Q 3.56 3.03 8.50 7.07 VK1AAVH1A24.60 3.25 7.06 5.52

Example 3 Antibody Avidity and Number of Available Epitopes onEndoglin-Expressing Cells

Antibody avidity and number of available epitopes on endoglin-expressingcells can be assessed utilizing Scatchard plot analyses using standardprotocols.

Briefly, Scatchard plot analyses of direct binding of radiolabeledhumanized anti-endoglin antibodies to endoglin-expressing KM-3 leukemiacells and sub-confluent proliferating HUVECs are carried out. Thepurified anti-endoglin antibodies are individually radiolabeled with¹²⁵I using Iodo-Gen and according to standard methods known to thoseskilled in the art. The radiolabeled humanized anti-endoglin antibodiesare assayed for the mean number of iodine atoms per IgG molecule.Titration experiments are carried out using a fixed amount (0.1 μg) ofeach ¹²⁵I-labeled mAb and 2-fold serial increments ofendoglin-expressing HUVEC cells to determine antigen-binding activity.Analysis of Scatchard plot of binding data is carried out according toknown methods. An equilibrium constant and an average maximal number ofmAb bound/cell are estimated by this analysis.

Example 4 Western Blot Assay for Anti-endoglin Antibody Activity

The ability of humanized anti-endoglin antibodies to modifyintracellular signaling in proliferating endothelial cells that expressCD105 can be assayed via western blots to detect the phosphorylation ofthe proteins involved in the CD105 signaling pathway.

Western blot analyses are performed to identify phosphorylated Smad1/5/8or Smad2/3 according to known western blotting techniques inuntransfected endothelial cells. Primary antibodies againstphosphorylated Smad1, Smad2, Smad5, Id1 (Santa Cruz) and endoglin areutilized to detect molecules in samples. Detection is performed byenhanced chemoluminescence (ECL).

Example 5 Inhibition of HUVEC growth and ³H-Thymidine IncorporationAssay

A number of assays are available to assess inhibition of cell growth.

In one example, the HUVEC cell line E6/E7 P3-17 was cultured in EBM2media with supplements (Lonza-Clonetics) containing 5% fetal calf serum.Cells were cultured in 75-cm² flasks (Falcon, Becton-Dickinson, FranklinLakes, N.J.) in a CO₂ incubator at 37° C. under subconfluent conditions.Cells are detached by incubating with Hanks' balanced salt solution with15 mM EDTA in 25 mM HEPES buffer, pH=7.3, at 37° C. for 15 min. Afterwashing twice with ice-cold PBS, cells are re-suspended in endothelialcell growth medium at a concentration of 25,000 cells/mL. In additionalexperiments, human umbilical vein endothelial cells (HUVECs) aresuspended and cultured in an endothelial cell growth medium free of FBSand bovine brain extracts. A 200 μl aliquot of cell suspensioncontaining 2,500 cells is seeded to each well of 96-well culture plates.Cells are cultured at 37° C. in a CO₂ incubator overnight before 100ug/mL of humanized anti-endoglin antibody VK1AAVH1A2 or, control IgG orPBS are added in triplicate. Culture plates are kept in the incubatorfor 72 hr, during which fresh media and humanized anti-endoglinantibody, control IgG or PBS are replaced every 24 hr. ³H-thymidine (1μCi) is added into each well and the plates are incubated for 20 hr.Cells are washed with PBS followed by treatment with 100 μl/welltrypsin-EDTA (0.05% trypsin, 0.53 mM EDTA) at 37° C. for 15 min. Cellsare harvested onto glass fiber filters (Wallac Printed FiltermatA) usingHarvester 96 (TOMTEC, Hamden, Conn.) and ³H-radioactivity is determinedin a Trilux 1540 MicroBeta Liquid Scintillation and Luminescence Counter(Wallac, Turku, Finland). In a second example, the cells used were aprimary culture of HUVEC cells, HUVEC 2517C, Humanized TRC105 antibodyinhibited the growth of the HUVEC cell line E6/E7 and the primary HUVECculture, HUVEC 2517C derived from a single donor, compared to antibodycontrol and PBS (Table 3).

TABLE 3 Inhibition of human endothelial cell growth byhumanized/deimmunized anti-endoglin antibody VK1AAVH1A2. E6/E7 cellsMean counts Standard % Inhibition Condition per minute deviation versusPBS PBS 18320 173 — Control IgG 18061 172 0.9 Chimeric 14452 1348 20.7Humanized/deimmunized 14025 983 23.1 anti-endoglin antibody VK1AAVH1A2

Example 6 Assay for Inhibition of Cell Migration by Anti-EndoglinAntibodies

Migration (chemokinesis) as a measure of cell proliferation andactivation is measured using a Boyden chamber.

Briefly, cell migration is assessed as follows: a Costar nucleoporefilter (8 mm pore) is coated with fibronectin overnight at 4° C. Thechamber is washed with phosphate-buffered saline (PBS) and the lowerchamber was filled with DMEM with or without serum and with or withoutTGF-β3. Cells are trypsinized and suspended at a final concentration of50,000 cells/ml in DMEM with anti-endoglin antibody. A 150 μl aliquot ofthe cell suspension is added to the upper chamber and incubated at 37°C. After 16 hrs, the cells are washed and the upper surface is wiped toremove the non-migrating cells. The membranes are fixed in methanol,washed with water, stained and the numbers of cells present on the lowersurface are counted.

Example 7 ADCC Assay for Humanized/Deimmunized Anti-Endoglin Antibodies

The anti-endoglin antibodies described herein can be assessed withrespect to their ability to bind to IL-2 activated natural killer (NK)cells and to induce antibody dependent cell-mediated cytotoxicity (ADCC)of HUVECs using, for example, the following protocols.

NK Isolation and Generation of IL-2 Activated NK Cells

PBMC are isolated and allowed to rest for 24 hrs at 4° C. in RPMI with10% FBS. PBMC are then placed in RPMI with 2% FBS (Total Volume=50 mL),and 10 mL of the cell suspension are plated in a petri dish. PBMC areincubated for 2 hrs at 37° C. and the non-adherent cells are collected.NK cells are cultured at 8×10⁶/mL with 1000 U/mL IL-2 for 48 hrs,followed by normal culturing for 5-8 days before use in an ADCC assay.

Cytotoxicity and ADCC Assays

NK cells are scraped from the culture and collected in a 50 mL conicaltube. Cells are washed once with RPMI Complete media and spun at 1200rpm for 10 minutes. NK cells are then resuspended in 5 mL RPMI Completemedia and counted. Prior to performing the assay, the NK cell count isnormalized to an effector: target ratio of 10:1. Normalized NK cells areplated and 10 μL of anti-endoglin antibody is added into designatedwells and incubated for 30 minutes at 37° C. Control samples includeuntreated or control-antibody treated cell populations. All samples andcontrols are tested in quintiplicate.

Target cells of interest are collected (HUVEC cells), washed, spun at1200 rpm for 10 minutes, and re-suspended in 5 mL RPMI Complete media.Target cells are washed again and re-suspended in Serum Free RPMI to afinal concentration of 1×10⁶ cells/mL. Target cells are then labeledwith a final concentration of 5 ug/mL Calcein AM for 1 hr at 37° C.,followed by two washes with RPMI Complete media. Target cells are thenre-suspended and added to the NK cell wells. The target cell/NK cellcombination is incubated at 37° C. for 4 hours. After incubation, theplates are spun at 1200 rpm for 5 minutes and cells are washed andresuspended in DPBS. The fluorescence is read using Excitation/Emissionof 450/530 nm and the emission is a measure of the cell killing mediatedby the antibodies. The mean fluorescence intensity and standarddeviation are calculated and used to calculate % ADCC according thefollowing formula:

% ADCC=100%*[(f_(sample)−f_(media))−(f_(isotype control)−f_(Triton))],

where:

f_(sample)=mean fluorescence in wells containing anti-endoglin antibody

f_(media)=mean fluorescence in wells containing media without antibody

f_(isotype control)=mean fluorescence in wells containing isotypecontrol IgG

f_(Triton)=mean fluorescence in wells containing Triton detergent (tolyse target cells)

Humanized/deimmunized antibody VK1AAVH1A2 demonstrated dose dependentADCC of HUVECs that was significantly greater than isotype controlantibody (Table 4).

TABLE 4 ADCC of humanized/deimmunized anti-endoglin antibody VK1AAVH1A2versus isotype matched control IgG on HUVEC cells. ADCC of TestCondition HUVECs (%) Standard Deviation Isotype Control (2 ug/mL) 3.44.7 VK1AAVH1A2 (0.4 ug/mL) 14.6 2.1 VK1AAVH1A2 (0.08 ug/mL) 14.6 2.1VK1AAVH1A2 (0.016 ug/mL) 12.6 4.1 VK1AAVH1A2 (0.0032 ug/mL) 8.4 4.1VK1AAVH1A2 (0.00064 ug/mL) 7.6 2.0

Example 8 Effect of Humanized/Deimmunized Anti-Endoglin Antibodies on aMurine Model of Choroidal Neovascularization

The effect of humanized/deimmunized anti-endoglin antibodies can beassessed in a murine model of choroidal neovascularization.

Briefly, 4 to 5 week old C57BL/6 mice are anesthetized with ketaminehydrochloride (100 mg/kg) and the pupils dilated with 1% tropicamide(Alcon Laboratories, Inc Fort Worth, Tex.). Three burns of a 532-nmdiode laser photocoagulation (75-pm spot size, 01-second duration, 120mW) are delivered to each retina using the slit lamp delivery system ofa photocoagulator (OcuLight; Iridex, Mountain View, Calif.) and ahandheld cover slip as a contact lens. Burns are performed in the 9, 12and 3 o'clock positions of the posterior pole of the retina. Productionof a bubble at the time of lasering, which indicates rupture of Bruch'smembrane, is an important factor in obtaining choroidalneovascularization (CNV); thus only burns in which a bubble is producedare included in the study.

Four independent experiments are performed to investigate the effect ofintraocular injections on day 0 after rupture of Bruch's membrane. Micein Group 1 are given an intraocular injection of about 0.5 to about 5 μgof a anti-endoglin antibody or antigen-binding fragment in 1 μl, of PBSin one eye and 1 μl of PBS in the fellow eye. Group 2 mice are given anintraocular injection of about 1.5 to about 10 μg of anti-endoglinantibody or antigen-binding fragment in 1 μl of PBS in one eye and 1 μLof PBS in the fellow eye. Group 3 mice are given an intraocularinjection of about 5 to about 25 μg of anti-endoglin antibody orantigen-binding fragment in one eye and 1 μl of PBS in the fellow eye.Group 4 receive PBS in both eyes.

After 14 days, mice are anesthetized and perfused withfluorescein-labeled dextran (2×10⁶ average molecular weight,Sigma-Aldrich) and choroidal flat mounts are prepared. Briefly, the eyesare removed, fixed for 1 hour in 10% phosphate-buffered formalin, andthe cornea and lens are removed. The entire retina is carefullydissected from the eyecup, radial cuts are made from the edge of theeyecup to the equator in all four quadrants, and the retina isflat-mounted in aqueous mounting medium (Aquamount; BDH, Poole, UK).Flat mounts are examined by fluorescence microscopy (Axioskop; CarlZeiss Meditec, Thornwood, N.Y.), and the images are digitized with athree charge-coupled device (CCD) color video camera (1K-TU40A, Toshiba,Tokyo, Japan). Frame grabber image-analysis software is used to measurethe area of each CNV lesion. Statistical comparisons are made usingANOVA with Dunnett's correction for multiple comparisons.

Example 9 Anti-angiogenic Therapy of Preformed Human Breast CancerTumors in Human Skin Grafted into SCID Mice

The effect of the humanized/deimmunized anti-endoglin antibodiesdescribed herein can be assessed with respect to their anti-angiogeniceffect on preformed human breast cancer tumors grown in human skingrafted into SCID mice.

Briefly, MCF-7 cells (8×10⁶ cells in 0.1 ml PBS) are transplantedintradermally into human full-thickness skin grafted into SCID mice whenthe grafts showed no signs of inflammation, contraction or rejection.The mice are left untreated until distinct palpable tumors (3 to 6 mm indiameter in most cases) appear. Mice with distinct tumors are dividedinto groups for the therapeutic studies. Humanized/deimmunizedanti-endoglin monoclonal antibody (mAb) and an isotype-matched controlIgG are diluted with sterile PBS containing mouse serum albumin (0.05%final concentration). For the antibody therapy, 1 to 20 mg/kganti-endoglin antibody or control IgG is intravenously (i.v.)administered via the tail vein of mice. The administration is givenevery two to three days.

During the treatment, mice are monitored daily for tumor size andmorbidity. Mice are weighed twice a week using an electronic balance(OHAUS™ Model GT210). Tumor size is measured three times a week using anelectronic caliper (PRO-MAX 6 inch caliper; Fowler Co., Newton, Mass.)connected to a computer using OptoDemo™ software (Fowler Co.). Themeasured tumor diameters are converted to tumor volumes using thefollowing formula: V=length×width×height×pi/6. Statistical analysis ofthe data for the comparison of different groups of mice is carried outusing Student's t-test.

Example 10 Mouse Model of Ovarian Cancer

To determine the ability of humanized/deimmunized anti-endoglinantibodies, or antigen-binding fragments thereof, to treat ovariancancer, an ovarian cancer cell line can be used in SCID or nude mice.

Briefly, ovarian cancer cells are implanted into SCID or nude mice togenerate ovarian tumors. Groups of mice bearing established tumors aretreated by i.v. administration of escalating doses (starting at 1.8mg/kg body weight) of humanized/deimmunized anti-endoglin antibody orcontrol IgG. The treatment is performed 2 or 3 times per week. A VEGFinhibitor and/or other anticancer agent may be used in some or allgroups. The mice are monitored and tumor growth is measured 2 or 3 timesper week.

Example 11 Mouse Model of Colorectal Cancer

To determine the ability of humanized/deimmunized anti-endoglinantibodies, or antigen-binding fragments thereof, to treat colorectalcancer, a colorectal cancer cell line can be used in SCID, nude orimmunocompetent mice.

Briefly, colorectal cancer cells are implanted into SCID, nude orimmunocompetent mice to generate colorectal tumors. Groups of micebearing established tumors are treated by i.v. administration ofescalating doses (starting at 1.8 mg/kg body weight) ofhumanized/deimmunized anti-endoglin antibody or control IgG. Thetreatment is performed 2 or 3 times per week. A VEGF inhibitor and/orother anticancer agent may be used in some or all groups. The mice aremonitored and tumor growth is measured 2 or 3 times per week. Tumors maybe imaged by standard imaging test, including PET and ultrasound.Treated tumors may be explanted to assess intracellular signalingpathways or vascularity by immunohistochemistry.

Example 12 Mouse Model of Kidney Cancer

To determine the ability of humanized/deimmunized anti-endoglinantibodies or antigen-binding fragments thereof to treat kidney cancer,a kidney cancer cell line is used in SCID or nude mice.

Briefly, kidney cancer cells are implanted into SCID or nude mice togenerate kidney tumors. Groups of mice bearing established tumors aretreated by i.v. administration of escalating doses (starting at 1.8 μg/gbody weight) of humanized/deimmunized anti-endoglin antibody or controlIgG. The treatment is performed at 3-day intervals for the first threeinjections and at a 7-day interval for the fourth injection. A VEGFinhibitor and/or other anticancer agent may be used in some or allgroups. The mice are monitored and tumor growth is measured viasacrifice of animals on a weekly basis.

Example 13 Mouse Model of Myeloma

To determine the ability of humanized/deimmunized anti-endoglinantibodies or antigen-binding fragments thereof to treat myeloma, amyeloma cell line is used in SCID or nude mice.

Briefly, myeloma cancer cells are implanted into SCID or nude mice togenerate myeloma tumors. Groups of mice bearing established tumors aretreated by i.v. administration of escalating doses (starting at 1.8mg/kg body weight) of humanized/deimmunized anti-endoglin antibody orcontrol IgG. The treatment is performed 2 or 3 times per week. A VEGFinhibitor and/or other anticancer agent may be used in some or allgroups. The mice are monitored and tumor growth is measured 2 or 3 timesper week.

Example 14 Mouse Model of Sarcoma

To determine the ability of humanized/deimmunized anti-endoglinantibodies or antigen-binding fragments thereof to treat sarcoma, asarcoma cell line is used in SCID or nude mice.

Briefly, sarcoma cancer cells are implanted into SCID or nude mice togenerate sarcoma tumors. Groups of mice bearing established tumors aretreated by i.v. administration of escalating doses (starting at 1.8mg/kg body weight) of humanized/deimmunized anti-endoglin antibody orcontrol IgG. The treatment is performed 2 or 3 times per week. A VEGFinhibitor and/or other anticancer agent may be used in some or allgroups. The mice are monitored and tumor growth is measured 2 or 3 timesper week.

Example 15 Mouse Model of Breast Cancer

To determine the ability of a humanized/deimmunized anti-endoglinantibody to treat breast cancer, a breast cancer cell line is used inSCID or nude mice.

Briefly, breast cancer cells are implanted into SCID or nude mice togenerate breast tumors. Groups of mice bearing established tumors aretreated by i.v. administration of escalating doses (starting at 1.8mg/kg body weight) of a humanized/deimmunized anti-endoglin antibody.Control animals are administered a control IgG. The treatment isperformed 2 or 3 times per week. A VEGF inhibitor and/or otheranticancer agent may be used in some or all groups. The mice aremonitored and tumor growth is measured 2 to 3 times per week.

Example 16 Clinical Trial of combination therapy for Colorectal Cancer

This example describes a randomized, blinded, placebo-controlled,multicenter, Phase 2 study designed to provide a preliminary assessmentof the safety and efficacy of a humanized/deimmunized anti-endoglinantibody in patients with colorectal cancer. Approximately about100—about 800 patients are enrolled, with about 50—about 400 patientsbeing assigned to a treatment group and about 50—about 400 patientsassigned to a placebo group. The trial will consist of theadministration of intravenous repeating doses of humanized/deimmunizedanti-endoglin antibody at about 0.1—about 20 mg/kg or placebo every one,two or three weeks for 6-10 cycles. A VEGF inhibitor and/or otheranticancer agent may be used in all groups. The time frame of the studyis estimated at about 6 months to about 5 years, with continued therapyfor responders as indicated at the end of the initial study. Additionaloutcome measures are as follows:

Primary outcome measure: overall response rate. One goal of the study isto demonstrate an increase progression-free survival by 35% withhumanized/deimmunized anti-endoglin antibody.

Secondary outcome measures that can be assessed include overall responserate, duration of response, overall survival, serious and non-seriousadverse events. For example, a treatment may prevent progression of thedisease (i.e., stasis) or may result in an improvement. Alternately, orin addition, other goals can be measured with respect to one or more ofthe following: decreased tumor burden, decreased vascularity, reducedside effects, decreased adverse reactions, and/or increased patientcompliance.

Example 17 Clinical Trial of combination therapy for Myeloma

This example describes a randomized, blinded, placebo-controlled,multicenter, Phase 2 study designed to provide a preliminary assessmentof the safety and efficacy of combining humanized/deimmunizedanti-endoglin antibody with bortezomib in patients with myeloma.Approximately about 100—about 800 patients are enrolled, with about50—about 400 patients being assigned to a treatment group and about50—about 400 patients assigned to a placebo group. The trial willconsist of the administration of intravenous repeating doses ofhumanized/deimmunized anti-endoglin antibody at about 1—about 20 mg/kgor placebo every one, two or three weeks combined with bortezomib atabout 1.3 mg/kg weekly. The time frame of the study is estimated atabout 6 months to about 5 years, with continued therapy for respondersas indicated at the end of the initial study. Additional outcomemeasures are as follows:

Primary outcome measure: overall response rate. One goal of the study isto demonstrate an increase overall response rate from about 40% withbortezomib plus placebo to about 60% (or more) with bortezomib plushumanized/deimmunized anti-endoglin antibody.

Secondary outcome measures that can be assessed include duration ofresponse, progression free survival, overall survival, serious andnon-serious adverse events. For example, a treatment may preventprogression of the disease (i.e., stasis) or may result in animprovement. Alternately, or in addition, other goals can be measuredwith respect to one or more of the following: decreased tumor burden,decreased vascularity, reduced side effects, decreased adversereactions, and/or increased patient compliance.

Example 18 Clinical Trial of combination therapy for Kidney Cancer

This example describes a randomized, blinded, placebo-controlled,multicenter, Phase 2 study designed to provide a preliminary assessmentof the safety and efficacy of combining humanized/deimmunizedanti-endoglin antibody with sunitinib (Sutent®) in patients with renalcell cancer (kidney cancer). Approximately about 100—about 800 patientsare enrolled, with about 50—about 400 patients being assigned to atreatment group and about 50—about 400 patients assigned to a placebogroup. The trial will consist of the administration of intravenousrepeating doses of humanized/deimmunized anti-endoglin antibody at about0.1—about 20 mg/kg or placebo every one, two or three weeks combinedwith sunitinib at about 5—about 50 mg administered daily for 4 weeks,with 2 weeks off prior to repeating the 4 week dosage cycle. The timeframe of the study is estimated at about 6 months—about 5 years, withcontinued therapy for responders as indicated at the end of the initialstudy. Additional outcome measures are as follows:

Primary outcome measure: progression-free survival. One goal of thestudy is to demonstrate an increase in progression free survival fromabout 9-13 months in the sunitinib plus placebo arm to about 14-18months (or more) in the sunitinib plus humanized/deimmunizedanti-endoglin antibody arm.

Secondary outcome measures that can be assessed include response rate,duration of response, time to tumor progression, overall survival,serious and non-serious adverse events. For example, a treatment mayprevent progression of the disease (i.e., stasis) or may result in animprovement. Alternately, or in addition, other goals can be measuredwith respect to one or more of the following: decreased tumor burden,decreased vascularity, reduced side effects, decreased adversereactions, and/or increased patient compliance.

Example 19 Clinical Trial of combination therapy for HepatocellularCancer

This example describes a randomized, blinded, placebo-controlled,multicenter, Phase 2 study designed to provide a preliminary assessmentof the safety and efficacy of combining humanized/deimmunizedanti-endoglin antibody with sorafenib (NEXAVAR®) in patients withhepatocellular cancer (liver cancer). Approximately about 100—about 800patients are enrolled, with about 50—about 400 patients being assignedto a treatment group and about 50—about 400 patients assigned to aplacebo group. The trial will consist of the administration ofintravenous repeating doses of humanized/deimmunized anti-endoglinantibody at about 0.1—about 20 mg/kg or placebo every one, two or threeweeks combined with sorafenib at about 400 mg daily for 3-6 cycles oruntil progression. The time frame of the study is estimated at about 6months to about 5 years, with continued therapy for responders asindicated at the end of the initial study. Additional outcome measuresare as follows:

Primary outcome measures: progression-free survival. One goal of thestudy is to demonstrate an increase in progression free survival fromabout 3-9 months in the sorafenib plus placebo arm to about 6-12 months(or more) in the sorafenib plus humanized/deimmunized anti-endoglinantibody arm.

Secondary outcome measures that can be assessed include duration ofresponse, time to tumor progression, overall survival, serious andnon-serious adverse events. For example, a treatment may preventprogression of the disease (i.e., stasis) or may result in animprovement. Alternately, or in addition, other goals can be measuredwith respect to one or more of the following: decreased tumor burden,decreased vascularity, reduced side effects, decreased adversereactions, and/or increased patient compliance.

Example 20 Clinical Trial of combination therapy for Kidney Cancer

This example describes a randomized, blinded, placebo-controlled,multicenter, Phase 2 study designed to provide a preliminary assessmentof the safety and efficacy of combining humanized/deimmunizedanti-endoglin antibody with bevacizumab (AVASTIN®) in patients withrenal cell cancer (kidney cancer). Approximately about 100—about 800patients are enrolled, with about 50—about 400 patients being assignedto a treatment group and about 50—about 400 patients assigned to aplacebo group. The trial will consist of the administration ofintravenous repeating doses of humanized/deimmunized anti-endoglinantibody at about 0.1—about 20 mg/kg or placebo every one, two or threeweeks combined with bevacizumab at about 7.5, about 10, or about 15mg/kg administered intravenously every two weeks. The time frame of thestudy is estimated at about 6 months to about 5 years, with continuedtherapy for positive responders as indicated at the end of the initialstudy. Additional outcome measures are as follows:

Primary outcome measure: progression-free survival. One goal of thestudy is to demonstrate an increase in progression free survival fromabout 8-12 months in the bevacizumab plus placebo arm to about 13-18months (or more) in the bevacizumab plus humanized/deimmunizedanti-endoglin antibody arm.

Secondary outcome measures that can be assessed include overall responserate, duration of response, time to tumor progression, overall survival,serious and non-serious adverse events. For example, a treatment mayprevent progression of the disease (i.e., stasis) or may result in animprovement. Alternately, or in addition, other goals can be measuredwith respect to one or more of the following: decreased tumor burden,decreased vascularity, reduced side effects, decreased adversereactions, and/or increased patient compliance.

Example 21 Clinical Trial of combination therapy for Ovarian Cancer

This example describes a randomized, blinded, placebo-controlled,multicenter, Phase 2 study designed to provide a preliminary assessmentof the safety and efficacy of combining humanized/deimmunizedanti-endoglin antibody with Doxil® in patients with ovarian cancer.Approximately about 100—about 800 patients are enrolled, with about50—about 400 patients being assigned to a treatment group and about50—about 400 patients assigned to a placebo group. The trial willconsist of the administration of intravenous repeating doses ofhumanized/deimmunized anti-endoglin antibody at about 0.1—about 20 mg/kgor placebo every one, two or four weeks combined with Doxil at about 5to about 50 mg/m² administered once every 4 weeks The time frame of thestudy is estimated at 6 months to about 5 years, with continued therapyfor responders as indicated at the end of the initial study. Additionaloutcome measures are as follows:

Primary outcome measure: progression-free survival. One goal of thestudy is to demonstrate an increase in progression free survival fromabout 3-6 months in the Doxil® plus placebo arm to about 4-12 months (ormore) in the Doxil® plus humanized/deimmunized anti-endoglin antibodyarm.

Secondary outcome measures that can be assessed include duration ofresponse, time to tumor progression, overall survival, serious andnon-serious adverse events. For example, a treatment may preventprogression of the disease (i.e., stasis) or may result in animprovement. Alternately, or in addition, other goals can be measuredwith respect to one or more of the following: decreased tumor burden,decreased vascularity, reduced side effects, decreased adversereactions, and/or increased patient compliance.

Example 22 Clinical Trial of Platinum Based Combination Therapy forOvarian Cancer

This example describes a randomized, blinded, placebo-controlled,multicenter, Phase 2 study designed to provide a preliminary assessmentof the safety and efficacy of combining humanized/deimmunizedanti-endoglin antibody with platinum based chemotherapy in patients withovarian cancer. Approximately about 100—about 800 patients are enrolled,with about 50—about 400 patients being assigned to a treatment group andabout 50—about 400 patients assigned to a placebo group. The trial willconsist of the administration of intravenous repeating doses ofhumanized/deimmunized anti-endoglin antibody at about 0.1—about 20 mg/kgor placebo every one, two or three weeks combined with a platinum basedchemotherapy regimen (e.g., carboplatin and paclitaxel) by intravenousinfusion with courses repeating throughout the study. The time frame ofthe study is estimated at about 6 months—about 5 years, with continuedtherapy for responders as indicated at the end of the initial study.Additional outcome measures are as follows:

Primary outcome measure: progression-free survival. One goal of thestudy is to demonstrate an increase in progression free survival fromabout 12-18 months in the topotecan plus placebo arm to about 12-24months (or more) in platinum-based chemotherapy plushumanized/deimmunized anti-endoglin antibody arm.

Secondary outcome measures that can be assessed include duration ofresponse, time to tumor progression, overall survival, serious andnon-serious adverse events. For example, a treatment may preventprogression of the disease (i.e., stasis) or may result in animprovement. Alternately, or in addition, other goals can be measuredwith respect to one or more of the following: decreased tumor burden,decreased vascularity, reduced side effects, decreased adversereactions, and/or increased patient compliance.

Example 23 Use of Anti-Endoglin Antibodies for the Treatment of DiabeticRetinopathy Study Design

To evaluate the biologic activity of multiple intravitreal injections ofhumanized/deimmunized anti-endoglin antibodies in patients withcenter-involving clinically significant diabetic macular edema (DME) andto report any associated adverse events, a single-center, open-label,dose-escalating pilot study is initiated. Patients with DME involvingthe center of the macula and best-corrected visual acuity (BCVA) in thestudy eye between 20/40 and 20/400 are enrolled.

Study Treatment

Eligible patients are randomly assigned in a 1:1 ratio to receive threeintravitreal injections of humanized/deimmunized anti-endoglinantibodies (about 0.25 to 2.5 mg per each injection) administeredmonthly and observations are continued until month 24. Primary endpoints are the frequency and severity of ocular and systemic adverseevents. Secondary end points are 1) best corrected visual assessment asassessed with the Early Treatment Diabetic Retinopathy Study (ETDRS)chart, with the use of standardized refraction and testing protocol at astarting test distance of 2 m and 2) measurement of retinal thickness byoptical coherence tomography. The evaluating physician is unaware of thepatient's treatment assignment; the physician who administers theinjection is aware of the patient's treatment assignment regardinghumanized/deimmunized anti-endoglin antibody or sham treatment but isunaware of the dose of humanized/deimmunized anti-endoglin antibody.Other personnel at each study site (except for those assisting withinjections), patients, and personnel at the central reading center areunaware of the patient's treatment assignment.

Efficacy and Safety Analyses

Efficacy analyses are performed on an intention-to-treat basis among allpatients with the use of a last-observation-carried-forward method formissing data. For all pairwise comparisons, the statistical model isadjusted for baseline score for visual acuity (<55 letters vs.≧55letters). Between-group comparisons for dichotomous end points areperformed with the use of the Cochran chi-square test. Change frombaseline visual acuity is analyzed with the use of analysis-of-variancemodels. For end points for lesion characteristics,analysis-of-covariance models adjusting for the baseline value are used.The Hochberg-Bonferroni multiple-comparison procedure is used to adjustfor the two pairwise treatment comparisons for the primary end point.Safety analyses include all treated patients.

Conclusion

Humanized anti-endoglin antibodies will be a well-tolerated therapy forpatients with DME. This pilot study demonstrates thathumanized/deimmunized anti-endoglin antibody therapy has the potentialto maintain or improve best corrected visual acuity and reduce retinalthickness in patients with center-involved clinically significant DME.

Example 24 Clinical Trial of Anti-Endoglin Antibodies and Age-RelatedMacular Degeneration Study Design

At multiple sites in the United States, patients are enrolled in a2-year, prospective, randomized, double-blind, sham-controlled study ofthe safety and efficacy of repeated intravitreal injections ofhumanized/deimmunized anti-endoglin antibodies among patients withchoroidal neovascularization associated with age-related maculardegeneration. Primary efficacy analysis is performed at 12 months. Theprimary efficacy end point is the proportion of patients who had lostfewer than 15 letters (approximately 3 lines) from baseline visualacuity, as assessed with the Early Treatment Diabetic Retinopathy Study(ETDRS) chart, with the use of standardized refraction and testingprotocol at a starting test distance of 2 m. The eligibility of lesionsis confirmed by an independent central reading center with the use ofstandardized criteria and trained graders who are unaware of patients'treatment assignments. Patients provide written informed consent beforedetermination of their full eligibility. Screening may last as long as28 days.

To be included in the study, patients must be at least 50 years old;have a best corrected visual acuity of 20/40 to 20/320 (Snellenequivalent determined with the use of an ETDRS chart); have primary orrecurrent choroidal neovascularization associated with age-relatedmacular degeneration, involving the foveal center; have a type of lesionthat had been assessed with the use of fluorescein angiography andfundus photography as minimally classic or occult with no classicchoroidal neovascularization; have a maximum lesion size of 12optic-disk areas (1 optic-disk area equals 2.54 mm² on the basis of 1optic-disk diameter of 1.8 mm), with neovascularization composing 50% ormore of the entire lesion; and have presumed recent progression ofdisease, as evidenced by observable blood, recent vision loss, or arecent increase in a lesion's greatest linear diameter of 10% or more.There are no exclusion criteria regarding preexisting cardiovascular,cerebrovascular, or peripheral vascular conditions.

First Study

Fifty to 500 patients (50 to 500 eyes) with AMD will participated in thestudy at multiple sites. Eligible patients are randomly assigned in a1:1:1 ratio to receive humanized/deimmunized anti-endoglin antibodies ata dose of about 0.25 mg to 2.5 mg or a sham injection monthly (within 23to 37 days) for 2 years (24 injections) in one eye. The evaluatingphysician is unaware of the patient's treatment assignment; thephysician who administers the injection is aware of the patient'streatment assignment regarding humanized/deimmunized anti-endoglinantibody or sham treatment but is unaware of the dose ofhumanized/deimmunized anti-endoglin antibody. Other personnel at eachstudy site (except for those assisting with injections), patients, andpersonnel at the central reading center are unaware of the patient'streatment assignment. Intervention therapy (e.g., Verteporfinphotodynamic therapy) is allowed if the choroidal neovascularization inthe study eye becomes predominantly classic.

As the first step of treatment, the patients are to receive a fullophthalmic examination to establish a baseline of ocular health. Theophthalmic examination includes indirect ophthalmoscopy, slit-lampbiomicroscopy, peripheral retinal examination, intraocular pressuremeasurements, visual acuity (unaided and best corrected) symptomatology,fundus photography, fluorescein angiography, optical coherencetomography, electroretinography and A-scan measurements.

Following the preliminary examination, an intravitreal injection asdescribed above is given to a patient's affected eye manifesting AMD. Ifboth eyes are affected, they may be treated separately. The eye to betreated is injected with an ophthalmic solution.

After treatment, the patients' eyes are to be examined on days one (1),two (2), seven (7), fifteen (15), thirty (30) and sixty (60) and everymonth thereafter for 2 years. Because of the possibility ofreoccurrence, the patients should return for periodic examinations on amonthly basis thereafter. On each examination day the patient ismonitored for vitreous liquefaction. Additionally, the patients aremonitored for posterior vitreous detachments using indirectophthalmoscopy with scleral depression. Finally, the extent of AMDpresented by the patients is continuously monitored through periodicretinal examinations, optical coherence tomography and fluoresceinangiograms to monitor for the presence of subretinal fluid, blood,exudates, RPE detachment, cystic retinal changes, or the presence ofgrayish green subretinal neovascular membrane. Additional treatments maybe required if indicia of reoccurring neovascularization are observed.Additional treatments may be given on weekly or monthly basis. In apreferred embodiment, an initial treatment is followed by subsequenttreatments between 1-6 months apart.

Efficacy analyses are performed on an intention-to-treat basis among allpatients with the use of a last-observation-carried-forward method formissing data. For all pairwise comparisons, the statistical model isadjusted for baseline score for visual acuity (<55 letters vs.≧55letters) and subtype of choroidal neovascularization (minimally classicvs. occult with no classic disease). Between-group comparisons fordichotomous end points are performed with the use of the Cochranchi-square test. Change from baseline visual acuity is analyzed with theuse of analysis-of-variance models. For end points for lesioncharacteristics, analysis-of-covariance models adjusting for thebaseline value are used. The Hochberg-Bonferroni multiple-comparisonprocedure is used to adjust for the two pairwise treatment comparisonsfor the primary end point. Safety analyses include all treated patients.

Second Study

Patients manifesting age-related macular degeneration are treatedaccording to the methods of the First Study (see above) with anintravitreal injection of (1) humanized/deimmunized anti-endoglinantibody alone, (2) ranibizumab alone, (3) humanized/deimmunizedanti-endoglin antibody in combination with ranibizumab in the samecomposition or different compositions or (4) control antibody to reduceor prevent the development of neovascularization, macular disease, andretinal damage.

Conclusion

Humanized/deimmunized anti-endoglin antibodies will be a well-toleratedtherapy for patients with AMD. This clinical trial demonstrates thathumanized/deimmunized anti-endoglin antibody therapy has the potentialto maintain or improve best corrected visual acuity and reduce choroidalneovascularization in patients with AMD. Further, humanized/deimmunizedanti-endoglin antibodies will demonstrate superior activity compared toranibizumab and the combination of humanized/deimmunized anti-endoglinantibodies and ranibizumab therapy and will demonstrate increasedactivity versus either antibody alone.

Example 25 Systemic Toxicology in Cynomolgus Monkeys

Cynomolgus monkeys are utilized in a study to address the systemictoxicology of humanized/deimmunized anti-endoglin antibodies.

Briefly, monkeys are dosed weekly for three weeks with 10.0 mg/kg, 30.0mg/kg or 100.0 mg/kg of the humanized/deimmunized anti-endoglinantibody. Placebo animals are dosed on the same schedule with anappropriate solution in the absence of antibody. The doses areadministered as an intravenous bolus over 30 to 60 minutes and at leastsix animals are dosed at each dose level. Toxicology is assessed via oneor more of the following indications: body weight measurements, basicphysiologic clinical measurements, serial serum chemistry, hematologicevaluations and histopathological evaluations.

Example 26 Systemic Toxicology in Combination with bevacizumab inCynomolgus Monkeys

Cynomolgus monkeys are utilized in a study to address the systemictoxicology of humanized/deimmunized anti-endoglin antibodies incombination with ranibizumab (LUCENTIS®).

Briefly, monkeys are dosed weekly for three weeks with 10.0 mg/kg, 30.0mg/kg or 100.0 mg/kg of the humanized/deimmunized anti-endoglin antibodyin combination with about 10 mg/kg to 100 mg/kg of bevacizumab. Otheranimals receive either humanized/deimmunized anti-endoglin antibody orbevacizumab alone. Placebo animals are dosed on the same schedule withan appropriate solution in the absence of antibody. The doses areadministered as an intravenous bolus over 30 to 60 minutes and at leastsix animals are dosed at each dose level. Toxicology is assessed via oneor more of the following indications: body weight measurements, basicphysiologic clinical measurements, serial serum chemistry, hematologicevaluations and histopathological evaluations.

Example 27 Regional Toxicology Study in Cynomolgus Monkeys

Cynomolgus monkeys are utilized in a study to address the regionaltoxicology of humanized/deimmunized anti-endoglin antibodies.

Briefly, monkeys are dosed by intravitreal injection weekly for sixweeks with 0.25, 1.25 and 2.5 mg of humanized/deimmunized anti-endoglinantibody. Placebo animals are dosed on the same schedule with anappropriate solution in the absence of antibody. The doses areadministered as intravitreal injections and at least six animals aredosed at each dose level. Toxicology is assessed via one or more of thefollowing indications: body weight measurements, basic physiologicclinical measurements, serial serum chemistry, hematologic evaluationsand histopathological evaluations.

Combination Regional Toxicology Study

Cynomolgus monkeys are utilized in a study to address the toxicology ofhumanized/deimmunized anti-endoglin antibodies in combination withranibizumab (LUCENTIS®) when given by intravitreal injection.

Briefly, monkeys are dosed by intravitreal injection weekly for sixweeks with 0.25, 1.25 and 2.5 mg of humanized/deimmunized anti-endoglinantibody and 0.5 mg of ranibizumab (LUCENTIS®). Other animals receiveeither antibody alone, at the same dose and schedule. Placebo animalsare dosed on the same schedule with an appropriate solution in theabsence of antibody. The doses are administered as intravitrealinjections and at least six animals are dosed at each dose level.Toxicology is assessed via one or more of the following indications:body weight measurements, basic physiologic clinical measurements,serial serum chemistry, hematologic evaluations and histopathologicalevaluations.

Example 28 Sprouting Assays

Angiogenesis can be tested in a three-dimensional in vitro model ofsprouting. HUVECs are isolated from umbilical cords and grown in M199supplemented with 10% fetal bovine serum (FBS) (GIBCO, Carlsbad, Calif.)and endothelial cell growth supplement (ECGS) (BD Biosciences, Bedford,Mass.) at 3° C. and 5% CO₂, Passage 2 to 4 HUVEC are used for allexperiments (Passage 0 being the primary culture). Lung fibroblasts (LF)are routinely grown in DMEM (GIBCO, Carlsbad, Calif.) supplemented with10% FBS at 37° C. and 5% CO₂ and used between P10 and P15. Otherfibroblast lines, obtainable from ATCC, can also be used.

Preparing the Cells

HUVEC and fibroblasts are expanded in M199/10% FBS/Pen-Strep (1:100) 1to 2 days before beading. For HUVEC, medium is switched to EGM-2(Clonetics, Walkersville, Md.) the day before beading. For fibroblasts,medium is switched to EGM-2 the day before embedding. Beading requiresapproximately 400 HUVEC per bead. Fibroblasts are used at 20,000 cellsper well for a 24-well plate. Ninety-six-well plates can also be usedwith quantities scaled accordingly.

Cytodex 3 Bead Preparation

Cytodex 3 microcarrier beads, for example, can be used in the assay(Amersham Pharmacia Biotech, Piscataway, N.J.).

Dry beads (0.5 g) are hydrated and swollen in 50 ml PBS (pH=7.4) for atleast 3 hours at room temperature (RT) in a 50-ml tube and placed it ona rocker.

The beads are allowed to settle (about 15 min). The supernatant isdiscarded and the beads are washed for a few minutes in fresh PBS (50ml).

The wash PBS is discarded and replaced with fresh PBS:

The bead suspension is placed in a siliconized glass bottle (from e.g.,Windshield Wiper or Sigrnacote). The beads are sterilized by autoclavingfor 15 min at 115° C. and then stored at 4° C.

Reagents

Fibrinogen Solution

A fibrinogen solution is made by dissolving 2 mg/ml fibrinogen in DPBSin a 37° C. waterbath. The solution is then mixed by inverting the tuberather than vortexing. The percentage of clottable protein can bedetermined and adjusted accordingly. The solution is then passed througha 0.22-μm filter to sterilize.

Aprotinin

Lyophilized aprotinin can be reconstituted at 4 U/ml in DI water andsterile filtered. Aliquots of 1 ml each are made and stored at −20° C.

Thrombin

Thrombin is reconstituted in sterile water at 50 U/ml. Aliquots of 0.5ml are made and stored at −20° C.

Coating the Beads with HUVEC (Day 1)

HUVEC cells are trypsinized. Beads are allowed to settle (do notcentrifuge), the supernatant is aspirated, and the beads are brieflywashed in 1 ml of warm EGM-2 medium. Beads (2500) are mixed with 1×10⁶HUVEC in 1.5 ml of warm EGM-2 medium in a FACS tube and placedvertically in the incubator. (This will be enough for approximately 10wells; scale up if needed).

The mixture is incubated for 4 hours at 37° C., inverting and mixing thetube every 20 min. (beads should look like mini golf balls after beadingwhich indicates sufficient coating for sprouting).

After 4 hours, the coated beads are transferred to a T25 tissue cultureflask (Falcon, Bedford, Mass.) and incubated overnight in 5 ml of EGM-2medium at 37° C. and 5% CO₂.

Embedding Coated Beads in Fibrin Gel (Day 0)

A 2.0 mg/ml fibrinogen solution is prepared as described above and 0.15Units/ml of aprotinin are added to the fibrinogen solution.

Coated beads are transferred to a 15 mL conical tube and the beads areallowed to settle.

Beads are resuspended in 1 ml of EGM-2 medium and transferred to a1.5-ml centrifuge tube. The beads are washed three times with 1 ml ofEGM-2 medium, mixing by pipetting up and down slowly with a P1000pipette. The beads are counted on a coverslip and resuspended in afibrinogen solution at a concentration of 500 beads/ml.

Thrombin (0.625 Units/ml) is added to each well of a 24-well plate. Thefibrinogen/bead suspension (0.5 ml) to each well changing the pipettetip for each well.

The thrombin and the fibrinogen/beads are mixed by pipetting up and downgently about four to five times; avoid creating bubbles in the fibringel. Control samples either are treated in the absence of antibodies orone or more control antibodies. Test samples are treated withanti-endoglin antibodies alone, anti-VEGF antibodies alone, or acombination thereof. Multiple concentrations of agents can be tested.The fibrinogen/bead solution is allowed to clot for 5 minutes at roomtemperature and then at 37° C./5% CO₂ for 15 min. It is important thatthe plate not be disturbed during the first 5 min of clotting tominimize shearing fibrin, which can result in reduced sprouting.

EGM-2 (1 mL) is added to each well in a drop-wise fashion. Lungfibroblasts are seeded on top of the clot at a concentration of 20,000cells/well. Replace culture medium with fresh EGM-2 medium every otherday until desired growth is achieved.

When the fibrin gel is formed, tiny bubbles may be present in the gel;they will disappear in 3 to 4 days. Sprouting should be apparent betweenday 2 and 4. Lumen formation begins around day 4 to 5 and sproutscontinue to elongate. Newly formed tubes begin to branch around day 4 to6. By day 6 to 7, the microvessel-like structures begin to anastomosewith adjoining tubes; increasing the number of beads per well results inearlier anastomosis. Sprouting distance is measured by standardtechniques.

Example 29 Immunocytochemistry of Angiogenic Sprouts in Vitro

For endothelial cell (EC) nuclei staining, fibrin gels are washed twicewith 1× PBS and then fixed overnight in 2% paraformaldehyde. After twomore washes with 1×PBS, gels are then stained with4′,6-diamidino-2-phenylindole (DAPI) (Sigma, St. Louis, Mo.).

For immunostaining, lung fibroblasts (LF) are first removed through abrief treatment of the gels with 10× trypsin. Digestion is stopped withserum as soon as all fibroblasts are removed. Gels are then extensivelywashed with HBSS, 1× (Cellgro, Herndon, Va.). Cultures are then fixedfor 10 minutes in 10% formalin and permeabilized with 0.5% Triton X-100for 5 minutes. Non-specific binding is blocked with a solution of 5% BSAin PBS for 2 hours.

Primary antibodies are used at a 1/100 dilution in blocking buffer andincubated overnight at 4° C. After extensive washing, bound antibody isdetected by species-specific Alexa Fluor 488-conjugated or Alexa Fluor568-conjugated secondary antibodies at a 1/1000 dilution (MolecularProbes, Carlsbad, Calif.). Isotype-specific non-binding antibodies areused as a control. If high background occurs, the concentration ofprimary or secondary antibody can be reduced and, if necessary,incubation and/or washing times can be increased. F-actin is stainedwith TRITC-phalloidin (Sigma, St. Louis, Mo.) at a concentration of 0.2μM.

Phase-contrast and fluorescent images are captured on an IX70 Olympusmicroscope coupled with a digital camera. Fluorescent Z-series imagestacks are captured on a two-photon Carl Zeiss MicroImaging LSM 510 Metamicroscope and compiled into three-dimensional renderings with Metamorphsoftware (Universal Imaging Corporation, Downingtown Pa.). Thus,expression of various markers can be readily detected.

Fluorescent optical image stacks along the z-axis of the cultures can becaptured to create 3D representations of the vessels. The nuclei arestained by DAPI (green), and vessel walls are stained for vimentin(orange). Wide, hollow lumens are clearly visible, surrounded by asingle layer of endothelial cells. These images confirm that the lumenspresent in the in vitro assay are intercellular and not intracellularslits as is often seen in Matrigel assays. Furthermore, it can beconfirmed that the HUVECs are polarized, in that they have an apicalmembrane, facing the lumen, and a basal membrane, apposed to a collagenIV-rich basement membrane and the fibrin gel.

Example 30 Suppression of Choroidal Neovascularization in CynomolgusMonkeys

The effect of compositions described herein on laser-induced choroidalneovascularization is evaluated in adult cynomolgus monkeys.

In this experiment, (1) humanized/deimmunized anti-endoglin antibodyalone, (2) anti-VEGF antibody alone, (3) humanized/deimmunizedanti-endoglin antibody in combination with anti-VEGF antibody in thesame composition or different compositions or (4) control antibody isadministered by intravenous or intravitreal injection. Each animalreceives nine or ten laser burns to each retina, and the development ofactive choroidal neovascular lesions is assessed by fluoresceinangiography, once before the initiation of treatment and 15, 20 and 29days post-laser treatment. Compositions are administered intravenouslyonce per week, beginning one week before laser injury. Intravitrealinjections are made once every two weeks beginning one week beforelaser, or once, two weeks following laser, at which time active CNVlesions have already formed. Control animals receive weekly intravenousor biweekly intravitreal injections of placebo, beginning one weekbefore laser.

CNV lesions are visualized by fluorescein angiography and gradedaccording to standard procedures.

Example 31 Inhibition of Injury-Induced Corneal Neovascularization

Corneal neovascularization is induced in male C57BL/6 mice byintrastromal placement of 3 nylon sutures, or by chemical injury (NaOH)and mechanical debridement of the corneal epithelium. Multipleexperiments are conducted in which (1) humanized/deimmunizedanti-endoglin antibody alone, (2) anti-VEGF antibody alone, (3)humanized/deimmunized anti-endoglin antibody in combination withanti-VEGF antibody alone in the same composition or differentcompositions or (4) control antibody is administered intraperitoneallyonce or at multiple time points immediately before or following injury.

The growth of corneal neovessels is evaluated by slit-lamp microscopyand histological evaluation. The vasculature is labeled with anendothelial cell specific fluorescein-conjugated lectin, andneovascularization is evaluated in corneal flat-mounts, as well as incross sections using PECAM immunohistochemistry. The presence of cornealedema is evaluated, using slit lamp microscopy, and corneal thickness ismeasured in cross-sections; increases in corneal thickness reflect theamount of edema. The numbers of polymorphonuclear leukocytes (PMN) andmacrophages are determined by staining cross-sections with HEMA-3 or ratanti-mouse F4/80 monoclonal antibody, respectively.

Example 32 Identification of T-cell epitopes in Humanized Anti-endoglinAntibodies

Sequences of humanized variable regions were tested by iTope™ analysis.Humanized variable region sequences were divided into overlapping9-15mer peptides. The variable region sequences were analyzed forpromiscuous high affinity binding to human MHC class II (potential Tcell epitopes) using iTope™, an in silico analytic tool that determinesthe affinity of peptides for MHC Class II by computational analysis.Sequences with the lowest frequencies of potential T cell epitopes fromthe iTope™ analysis are identified as leads for generation of ahumanized antibody. The selected humanized variable region sequences mayredesigned through inclusion of mutations in order to remove potential Tcell epitopes. Mutations are designed using iTope™ to reduce oreliminate MHC class II binding. Alternatively, germ-line human sequencescan be substituted at sites of potential T cell epitopes or alternativesequences may be substituted.

FIGS. 19-23 present the predicted binding of 9mer peptides for thehumanized anti-endoglin antibody containing the light chain HuVK_v0 andthe heavy chain HuVH_v0, noted in FIG. 4.

Example 33 Design of Anti-CD105 Humanized/Deimmunized Antibodies

This example describes the design of therapeutic monoclonal,humanized-deimmunized antibodies targeting human CD105 that exhibitreduced immunogenicity.

The promiscuous high affinity MHC class H binding sequences identifiedusing iTope™ (see Example 31) were further analyzed by iTope™ in orderto identify amino acid substitutions at key MHC class II pocketpositions that would reduce or eliminate peptide binding to MHC classII. Since all the sequences overlapped CDRs, consideration was alsogiven to the CDR location of the changes (potential antigen contactresidues) and the physicochemical characteristics of the original andreplacement amino acids. TCR contact residues and residues outside themain binding groove involved in the stabilization of peptide/MHC classII-TCR interactions were also considered for replacement.

In VHV1, a 9-mer peptide lying completely within CDR2 and starting atresidue 51 was identified as a promiscuous high affinity MHC class IIbinding peptide. The most successful method for elimination of MHC classII binding is to target the first amino acid of the 9-mer (the pocket 1or p1 position) where removal of the hydrophobic side-chain orreplacement with a hydrophilic side-chain eliminates MHC class IIbinding. However, this type of radical amino acid replacement may notalways be successful in retaining antibody affinity, hence secondarypocket positions (p4, p6, p7 or p9), alone or in combination, were alsoassessed. iTope™ analysis revealed that targeting the p4 position ofthis peptide by changing K52b to Q or R is predicted to significantlyreduce MHC class II binding while replacement of I51 at p1 with A ispredicted to remove binding entirely (Table 5).

TABLE 5 B1* B1* B1* B1* B1* B1* B1* B1* B1* B1* B* B* B* B* Sequence0101 0102 1501 1502 0301 0305 0306 0309 0401 0405 0404 0405 0408 0410WVGEIRSKASNHAT X X X O X X X X X X X WVGEIRSQASNHAT X X O X XWVGEIRSRASNHAT X X WVGEARSKASNHAT B1* B1* B1* B1* B1* B1* B1* B1* B1*B1* B1* B1* B1* B1* Sequence 0421 1101 1102 1104 1107 1114 1120 11281301 1304 1307 1321 0701 0801 WVGEIRSKASNHAT X X x X O X X O X X X O O XWVGEIRSQASNHAT X X O O WVGEIRSRASNHAT X X O WVGEARSKASNHAT Total B1* B1*B1* B1* B1* B5* Binding High Sequence 0802 0804 0806 0813 0817 0101Affinity Affinity WVGEIRSKASNHAT X X X X X 31 26 WVGEIRSQASNHAT O O 11 6WVGEIRSRASNHAT 6 4 WVGEARSKASNHAT 0 0 Table 5: Analysis of the effect ofsubstitutions on the immunogenic region of VHV1 using iTope™. The core9-mer peptide is underlined in the “sequence” column and substitutionsare highlighted in bold type. Flanking residues are not underlined. Thepredicted binding of each core 9-mer peptide to each MHC class IIalleles is indicated by “0” if the binding score was 0.55-0.6 and “X” ifthe binding score was >0.6. The numbers of MHC class II allelespredicted to bind are shown in the “total” and “high affinity” columns.Table 5 discloses SEQ ID NOS 106-109, respectively, in order ofappearance.

Crystal structures of antibody/antigen complexes suggest that I51 mayinfrequently contact with antigen; however a radical change of I to A (asubstitution for disrupting a p1 anchor position) at this position couldaffect the overall conformation of the CDR. Therefore, relativelyconservative changes at K52b (p4 anchor position) were also includedsince this residue is solvent exposed but may not contact antigen.Finally, additional mutations lying outside the CDR were also designed(G49 to A or S) to assess the destabilizing effect on peptide/MHC classII/TCR interactions. Table 6 lists the humanized andhumanized/deimmunized variant VH regions that were constructed; the SEQID NOS for the corresponding nucleotide and amino acid sequences areindicated next to the constructs.

TABLE 6 Construct Amino Acid Name Parental Sequence Substitutions SEQ IDNO VH1 VHV1 N/A 42 VH2 VHV2 N/A 43 VK1 VKV1 N/A 4 VK2 VKV2 N/A 5 VH1A2VHV1 I51A 89 VH1Q VHV1 K52bQ 90 VH1R VHV1 K52bR 91 VH1S VHV1 G49S 92VH1A VHV1 G49A 88 VK2AA VKV2 V19A + I48A 94 VK2AS VKV2 V19A + T51S 95VK2SA VKV2 T22S + I48A 96 VK2SS VKV2 T22S + T51S 97 VK1AA VKV1 V19A +I48A 93 VK1AS VKV1 V19A + T51S 102 VK1SA VKV1 T22S + I48A 103 VK1SS VKV1T22S + T51S 100

Two promiscuous high affinity MHC class II binding peptides wereidentified in VKV2 and VKV1. The first, with a p1 anchor at V19,partially overlaps CDR1 and the second, with a p1 anchor at 148,overlaps CDR2. Both p1 anchors lie outside the CDRs and were targeted bymutation to A, which may completely remove MHC class II binding (Table7). However, both these residues may be involved in the maintenance ofthe conformations of CDRs 1 and 2; therefore, additional mutations weredesigned that significantly reduced MHC class II binding (Table 7). Inboth cases, p4 residues were targeted by mutation of T to S. T22S alsolies outside the CDR and is less likely to affect CDR conformation thanV19A. T51 lies inside CDR2; however evidence from crystal structures ofantibodies complexed with antigen suggests that this residue rarelycontacts antigen. Table 6 lists the humanized and humanized/deimmunizedVK regions that were constructed.

TABLE 7 B1* B1* B1* B1* B1* B1* B1* B1* B1* B1* B* B* B* B* Sequence0101 0102 1501 1502 0301 0305 0306 0309 0401 0405 0404 0405 0408 0410DRVTITCRASSSV O X X X X O O O DRVTISCRASSSV X X X X DRATITCRASSSVPWITATSNLASGV O X X O O X X X X X X PWIYASSNLASGV O X O O PWAYATSNLASGVB1* B1* B1* B1* B1* B1* B1* B1* B1* B1* B1* B1* B1* B1* Sequence 04211101 1102 1104 1107 1114 1120 1128 0301 0304 0307 1321 0701 0801DRVTITCRASSSV O X X X X X X X X X X X X DRVTISCRASSSV X DRATITCRASSSVPWITATSNLASGV X X X O X X X PWIYASSNLASGV X O PWAYATSNLASGV X Toatl B1*B1* B1* B1* B1* B5* Alleles High Sequence 0802 0804 0806 0813 0817 0101Binding Affinity DRVTITCRASSSV X X X X O O 27 20 DRVTISCRASSSV 5 5DRATITCRASSSV 0 0 PWITATSNLASGV X O O 23  16 PWIYASSNLASGV 7 3PWAYATSNLASGV 0 0 Table 7: Analysis of the effect of substitutions onthe immunogenic regions of VKV2 or VKV1 using iTopeTM. The core 9-merpeptide is underlined in the “sequence” column and substitutions arehighlighted in bold type. Flanking residues are not underlined. Thepredicted binding of each core 9-mer peptide to each MHC class IIalleles is indicated by “0” if the binding score was 0.55-0.6 and “X” ifthe binding score was >0.6. The numbers of MHC class II allelespredicted to bind are shown in the “total” and “high affinity” columns.Table 7 discloses SEQ ID NOS 110-115, respectively, in order ofappearance.

Example 34

This example describes a method of screening anti-endoglin antibodiesfor T-cell epitopes. The interaction between MHC, polypeptide and T cellreceptor (TCR) provides the structural basis for the antigen specificityof T cell recognition. T cell proliferation assays test the binding ofpolypeptides processed from antibodies to MHC and the recognition ofMHC/polypeptide complexes by the TCR. In vitro T cell proliferationassays of the present example, involve the stimulation of peripheralblood mononuclear cells (PBMCs), containing antigen presenting cells(APCs) and T cells. Stimulation is conducted in vitro using intactanti-endoglin antibodies. Stimulated T cell proliferation is measuredusing ³H-thymidine (3H-Thy) and the presence of incorporated ³H-Thy isassessed using scintillation counting of washed fixed cells.

All humanized and humanized/deimmunized VH and VK region genes weresynthesized using a series of overlapping oligonucleotides that wereannealed, ligated and PCR amplified to give full length synthetic Vregions. The assembled variants were then cloned directly into AntitopeLtd.'s pANT expression vector system for IgG1 heavy chains and kappalight chains.

Purification of Antibodies

Anti-endoglin antibodies were purified from the supernatants ofmammalian cultures by protein A chromatography. Buffer exchange andprotein concentration was done using PBS pH=7.4. Anti-endoglin antibodywas further purified by size exclusion chromatography using a SephacrylS200 column (GE Healthcare, AMersham, UK). The major peak is collected,filter sterilized and shown to have endotoxin levels <5 EU/mg using anEndosafe-PTS (Charles River, Margate, UK). The purified antibodies arestored at 4 degrees Celsius. Final concentrations were determined by UVabsorption using calculated molar extinction coefficients, where A2801.0=1.62 mg/mL. Each antibody was then diluted to 100 ug/mL in AIMVculture medium.

Preparation and Selection of Donor PBMC

Peripheral Blood Mononuclear cells (PBMC) are isolated from healthycommunity donor buffy coats (from blood drawn within 24 hours) which areobtained from the UK National Blood Transfusion Service (Addenbrooke'sHospital, Cambridge, UK) according to approval granted by Addenbrooke'sHospital Local Research Ethics Committee. PBMC are isolated from buffycoats by Lymphoprep (Axis-shield, Dundee, Scotland) densitycentrifugation and CD8+ T cells are depleted using CD8+ RossetteSep™(StemCell Technologies, Inc.). Donors are characterized by identifyingHLA-DR haplotypes using a Biotest HLA SSP-PCR based tissue-typing kit(Biotest, Landsteinerstraβe, Denmark). T cell responses to a controlantigen, Keyhole Limpet Haemocyanin (KLH) (Pierce, Rockford, Ill., USA)are determined for a positive control. PBMC were then frozen and storedin liquid nitrogen until required. When required for use, cells arethawed rapidly in a water bath at 37° C. before transferring to 10 mlpre-warmed AIM V medium.

A cohort of 20 donors is selected to best represent the number andfrequency of HLA-DR allotypes expressed in the world population.Analysis of the allotypes expressed in the cohort against thoseexpressed in the world population revealed that coverage of >80% isachieved and that all major HLA-DR alleles (individual allotypes with afrequency >5% expressed in the world population) are well represented. Asummary of donor haplotypes is provided in FIG. 23, and a comparison ofthe frequency of donor allotypes used in the study versus those presentin the world population is made.

PBMCs from each donor are thawed, counted and viability assessed. Cellswere revived and resuspended in AIMV culture medium to 4−6×10⁶ PBMC/mL.For each donor, bulk cultures were established in which a total of 1 mLproliferation cell stock was added to a 24-well plate. A total of 1 mLof each diluted test sample was added to the PBMC to give a finalconcentration of 50 ug/mL per antibody sample. For each donor, apositive control (cells incubated with 100 ug/mL KLH) and a negativecontrol (cells incubated with culture media only) were also included.For the first 4 donors, an additional control was included to test formodulation of T cell responses by the test samples, where test sampleand KLH were added to the PBMC. Comparison of these samples with KLHalone can be used to assess the effects of the test samples onproliferation. Cultures were incubated for a total of 8 days at 37degrees Celsius with 5% carbon dioxide. On days 5, 6, 7 and 8, the cellsin each well are gently resuspended and three 100 uL aliquots aretransferred to individual wells of a round bottom 96 well plate. Thecultures are pulsed with 1 μCi ³-[H]-Thy (Perkin Elmer, Waltham, Mass.)in 100 uL AIMV culture medium and incubated for a further 18 hoursbefore harvesting onto filter mats using a TomTec Mach III cellharvester. Counts per minute (cpm) for each well are determined byMeltilex™ (Perkin Elmer®, Waltham, Mass., USA) scintillation counting ona Microplate Beta Counter (Perkin Elmer®, Waltham, Mass., USA) inparalux, low background counting mode.

Results are expressed as stimulation indices, where the stimulationindex (SI) is derived by division of the proliferation score (e.g.counts per minute of radioactivity) measured to the test anti-endoglinantibody by the score measured in cells not contacted with a testanti-endoglin antibody. All basal cpm for the control wells are abovethe minimum threshold for the assay of 150 cpm.

For proliferation assays, an empirical threshold of a stimulation index(SI) equal to or greater than 2 (SI≧2) has been previously establishedwhereby samples inducing proliferative responses above this thresholdare deemed positive (where included, borderline SIs≧1.90 arehighlighted). Extensive assay development and previous studies haveshown that this is the minimum signal to noise threshold allowingmaximum sensitivity without detecting large numbers of false positiveresponses. Positive responses are defined by the following statisticaland empirical thresholds:

-   -   1. Significance (p<0.05) of the response by comparing cpm of        test wells against medium control wells using unpaired two        sample student's t-test.    -   2. Stimulation index greater than 2 (SI≧2), where SI=mean of        test wells (cpm)/mean medium control wells (cpm).

In addition, intra-assay variation is assessed by calculating thecoefficient of variance and standard deviation (SD) of the raw data fromreplicate cultures.

Results for the EpiScreen time course proliferation assay with theanti-endoglin antibodies are shown in FIG. 24 and summarized in tabularform (Table 8). The chimeric antibody stimulated responses in 4 of 20donors (20% of the study cohort) and, although two of the donorresponses were borderline (1.92 and 1.95 for donors 11 and 17,respectively), they were significantly different from background(p<0.05). The humanized antibody VK1VH1 stimulated responses in 2 of 20donors (10% of the study cohort) including one borderline response (1.91for donor 20) that was significantly different from background (p<0.05).It is noteworthy that donors 11 and 20 responded to both of theseantibodies suggesting that there could be a shared T cell epitope. Incontrast, none of the donors in the study cohort responded positively tothe deimmunized anti-endoglin antibody VK1AA VH1A2. Results with thecontrol antigen KLH show that there was a good correlation betweenpositive and negative results, indicating a high level ofreproducibility in the assay.

TABLE 8 T cells stimulation, as a measure of immunogenicity, inducedculture with anti-endoglin antibodies and KLH, where “P*” indicateborderline stimuilation above baseline and “P” indicates a stimulationindex greater than 2. VK1AA Basal Donor No Chimeric VK1VH1 VH1A2 KLH CPM 1 P 7456  2 P* 2272  3 P 3943  4 P 2827  5 P 2029  6 P 1918  7 3870  8P 3110  9 P 1242 10 6042 11 P* P P 1696 12 P 3275 13 P 4644 14 P 1993 15P 2727 16 P 1781 17 P* P 3681 18 P 893 19 P P 1705 20 P P* P 2901Positive 4 (20%) 2 (10%) 0 (0%) 92 Responses:

Example 35 EpiScreen™ T Cell Epitope Mapping

EpiScreen™ is an ex vivo technology for measurement of T cell epitopesin whole antibodies or for mapping the sequence location of such T cellepitopes as described in more detail below.

EpiScreen Donor Selection

Peripheral Blood Mononuclear cells (PBMC) are isolated from healthycommunity donor buffy coats (from blood drawn within 24 hours) which areobtained from the UK National Blood Transfusion Service (Addenbrooke'sHospital, Cambridge, UK) according to approval granted by Addenbrooke'sHospital Local Research Ethics Committee. PBMC are isolated from buffycoats by Lymphoprep (Axis-shield, Dundee, Scotland) densitycentrifugation and CD8+ T cells are depleted using CD8+ RossetteSep™(StemCell Technologies, Inc.). Donors are characterized by identifyingHLA-DR haplotypes using a Biotest HLA SSP-PCR based tissue-typing kit(Biotest, Landsteinerstraβe, Denmark). T cell responses to a controlantigen, e.g., Keyhole Limpet Haemocyanin (KLH) (Pierce, Rockford, USA)are also determined for a positive control. A cohort of 54 donors isselected to best represent the number and frequency of HLA-DR allotypesexpressed in the world population. Analysis of the allotypes expressedin the cohort against those expressed in the world population revealedthat coverage of >80% is achieved and that all major HLA-DR alleles(individual allotypes with a frequency >5% expressed in the worldpopulation) are well represented. A summary of donor haplotypes isprovided, and a comparison of the frequency of donor allotypes used inthe study versus those present in the world population is made.

Donor details and haplotypes. Donor responses (SI) to KLH are tested intwo independent experiments. Test 1 is performed on freshly isolatedPBMC and an antibody is the re-test in the current study. Responses thatdid not produce the same result (i.e., positive or negative) in bothtests are highlighted. Donors with very low basal cpm (<150 cpm) areexcluded from the analysis.

EpiScreen Analysis: Proliferation Assays

EpiScreen™ is used to test overlapping peptides derived from thesequence of chimeric, humanized and humanized/deimmunized antibodies.Overlapping peptides are designed. A series of 128×15-mer peptidesoverlapping by 12 amino acids are synthesized together with 1×14-mer and1×11-mer and used to stimulate peripheral blood mononuclear cells (PBMC)derived from a cohort of 51 healthy donors using EpiScreen™ T cellepitope mapping. Individual peptides are tested in replicate culturesand responses are assessed using T cell proliferation assays to identifythe precise location of epitopes. PBMC from each donor are thawed,counted and assessed for viability. Cells are revived in roomtemperature AIM V culture medium (Invitrogen, Carlsbad, Calif.) beforeadjusting the cell density to 2.5×10⁶ PBMC/ml (proliferation cellstock). Peptides are dissolved in DMSO (Sigma-Aldrich, St Louis, Mo.,USA) to a final concentration of 10 mM. Peptide culture stocks are thenprepared by diluting into AIM V culture medium to a final concentrationof 5 μM. For each peptide and each donor, sextuplicate cultures areestablished by adding 100 μl of the peptide culture stocks to 100 μl ofproliferation cell stock in a flat bottomed 96 well plate. Both positiveand negative control cultures are also established in sextuplicate. Atotal of 9×96 well plates are used for each donor, and each plate issufficient to test 15 peptides with one negative control (carrier alone)in sextuplicate. On the final plate, a positive control is added.

Cultures are incubated for a total of 6 days before adding 0.5 μCi³[H]-Thymidine (Perkin Elmer®, Waltham, Mass., USA) to each well.Cultures are incubated for a further 18 hours before harvesting ontofilter mats using a TomTec Mach III cell harvester. Counts per minute(cpm) for each well are determined by Meltilex™ (Perkin Elmer®, Waltham,Mass., USA) scintillation counting on a Microplate Beta Counter (PerkinElmer®, Waltham, Mass., USA) in paralux, low background counting mode.

For proliferation assays, an empirical threshold of a stimulation index(SI) equal to or greater than 2 (SI≧2) has been previously establishedwhereby samples inducing proliferative responses above this thresholdare deemed positive (where included, borderline SIs≧1.90 arehighlighted). Extensive assay development and previous studies haveshown that this is the minimum signal to noise threshold allowingmaximum sensitivity without detecting large numbers of false positiveresponses. Positive responses are defined by the following statisticaland empirical thresholds:

-   -   1. Significance (p<0.05) of the response by comparing cpm of        test wells against medium control wells using unpaired two        sample student's t-test.    -   2. Stimulation index greater than 2 (SI≧2), where SI=mean of        test wells (cpm)/mean medium control wells (cpm).

In addition, intra-assay variation is assessed by calculating thecoefficient of variance and standard deviation (SD) of the raw data fromreplicate cultures.

Proliferation assays are set up in sextuplicate cultures (“non adjusteddata”). To ensure that intra assay variability is low, data is alsoanalyzed after removing the maximum and minimum cpm values (“adjusteddata”) and the SI of donor responses are compared using both data sets.Details of donor SIs from both adjusted and non-adjusted data sets areprepared. T cell epitopes are identified by calculating the averagefrequency of responses to all peptides in the study +2×SD (backgroundresponse rate). Any peptide(s) that induced proliferation above thisthreshold is considered to contain a T cell epitope.

In Silico iTope™ Analysis of Peptides

The sequences of peptides that are positive in the proliferation assayare analyzed using Antitope's predictive iTope™ software. This softwarepredicts favorable interactions between amino acid side chains of thepeptide and specific binding pockets within the MHC class II bindinggroove. The location of key binding residues is determined by generating10-mer peptides that overlapped by one amino acid spanning the longpeptide sequence. Each 10-mer is tested against Antitope's database ofMHC class II allotypes and scored based on their fit and interactionswith the MHC class II molecules. Peptides that produced a high bindingscore against a large number of alleles are considered to contain thecore 9mer.

Identification of T Cell Epitopes

All peptides identified using the EpiScreen™ Analysis described aboveare successfully synthesized for testing against 51 healthy donors (54donors are originally selected; donors may be excluded from the analysisdue to low basal cpm, i.e., below the cut off value of 150 cpm).Positive responses are defined by donors that produced a significant(p<0.05) response with a SI≧2 to any given peptide. Borderline responses(a significant (p<0.05) response with an SI≧1.90) are also included. Theoutputs from non-adjusted and adjusted data analyses are compared toensure that intra-assay variability is low and that positive responsesare not the result of spurious proliferation in individual wells. Theresults from each analysis showed little difference between the methods;consequently, the T cell epitope map is compiled using the adjusted dataanalysis. Donor stimulation indices from both non-adjusted and adjustedanalyses are prepared. T cell epitopes are identified by calculating theaverage frequency of the responses to all peptides in the study plustwice the standard deviation (termed ‘background response rate’). Thisis calculated to be 5.6% and is the equivalent of inducing a positiveresponse in three or more donors. Peptides inducing proliferativeresponses above this threshold are considered to contain a T cellepitope.

Immunogenicity Testing of Lead Variants Using EpiScreen™

Lead variants are purified and compared against the wild-typepolypeptide using EpiScreen™ time course T cell assays. A large numberof healthy donors representing the world population according toexpression of HLA allotypes are selected from a donor library asdescribed above. Donors are stimulated with each protein in separatebulk cultures containing 2−4×10⁶ CD8⁺ T cell depleted PBMC. Replicatesamples (of T blasts) are removed from bulk cultures on days 5-8, andproliferation along with IL-2 secretion (ELISPOT) is assessed. Tofurther validate the assessment between wild type and variants, thestudy cohort is supplemented with responding donors from the EpiScreen™T cell epitope mapping study (provided sufficient numbers of CD8⁺ T celldepleted PBMC remain).

In order to confirm loss of immunogenicity in lead variants, an analysisof T cell immunogenicity by EpiScreen™ time course T cell assays isundertaken as follows:

-   -   (i) Buffy coats from healthy donors (with >80% DRB1 allotypic        coverage for world population) are used to isolate PBMC which        contain physiological levels of APC and CD4⁺ T cells;    -   (ii) Each donor is tested against positive control antigens        including keyhole limpet haemocyanin (a potent neoantigen);    -   (iii) CD8⁺ T cells are depleted to exclude the detection of MHC        class I restricted T cell responses;    -   (iv) Lead variants and wild-type polypeptides are compared        against each other to evaluate relative capacity to activate T        cells CD4⁺ T cells;    -   (v) Data is analyzed using previously validated assay parameters        with positive responses of SI>2 supported by additional        information including statistical and frequency analysis;    -   (vi) Data from EpiScreen™ time course T cell assays provides        information on the magnitude and kinetics of T cell responses to        individual molecules;    -   (vii) Any remaining PBMC from donors that produce positive        responses is archived and is available for use in repeat testing        studies; and    -   (viii) An assessment is made of association between donor        allotype and responses to wild-type polypeptide and any        responses to variant leads.

Aspects of this invention may be embodied in other forms or carried outin other ways without departing from the spirit or essentialcharacteristics thereof. The present disclosure is therefore to beconsidered as in all aspects illustrated and not restrictive, and allchanges which come within the meaning and range of equivalency areintended to be embraced therein.

Example 36 Cross Reactivity of Anti-Endoglin Antibodies

Anti-endoglin antibodies have been demonstrated to be cross reactivewith endothelial cells from human and mouse (Matsuno et al, 1999).Humanized/deimmunized anti-endoglin antibodies are tested for theirability to bind to human and human and murine endothelium by theradioimmunoassay (RIA) according to the method of Haruta et al, 1986.Briefly, purified anti-endoglin antibodies are individually radiolabeledwith ¹²⁵I using Iodo-Gen and according to standard methods known tothose skilled in the art. The radiolabeled humanized/deimmunizedanti-endoglin antibodies are assayed for the mean number of iodine atomsper IgG molecule. Counts per minute are compared by testinganti-endoglin antibodies or isotype matched control IgG on cultures ofhuman and murine endothelial cells. Binding to subconfluent murine andhuman endothlial cells may also be demonstrated using with FITC labeledanti-endoglin antibody and analyzed by Becton Dickinson FACScan tocompare mean fluorescence intensity according to the method of Matsunoet al, 1999. Binding to murine endothelium may also be demonstrated byimaging the biodistribution of radiolabelled anti-endoglin antibody inmice bearing syngeneic tumors. Briefly, immunocompetent mice areimplanted with syngeneic 4T1 breast carcinomas. Tumors are allowed togrow to palpable size and animals are treated with antibody chelated toa radioisotope, such as ⁶⁴Cu. The distribution of labeled anti-endoglinantibody in tumor-bearing BALB/c mice by autoradiography or PET scanningis compared to the distribution of similarly labeled isotype controlledantibody. Tumor uptake of labeled antibody is reported relative touptake in solid organs and the blood.

1. An antibody, or antigen-binding fragment thereof, comprising a heavychain variable region having an amino acid sequence set forth as SEQ IDNO: 89 and a light chain variable region having an amino acid sequenceset forth as SEQ ID NO:
 93. 2. An antibody, or antigen-binding fragmentthereof, that binds endoglin, comprising a heavy chain variable regionhaving an amino acid sequence set forth as SEQ ID NO: 89 and a lightchain variable region having an amino acid sequence set forth as SEQ IDNO: 93, wherein: said heavy chain variable region further comprises oneor more modifications selected from the group consisting of asubstitution of glycine (G) by alanine (A) or serine (S) at position 49;a substitution of alanine (A) by isoleucine (I) at position 51; asubstitution of lysine (K) by arginine (R) or asparagine (O) at position52b; a substitution of leucine (L) by valine (V) at position 78utilizing the Kabat numbering system; and the light chain variableregion further comprises one or more modifications selected from thegroup consisting of a substitution of methionine (M) by leucine (L) atposition 4; a substitution of alanine (A) by valine (V) at position 19;a substitution of threonine (T) by serine (S) at position 22; asubstitution of alanine (A) by isoleucine (I) at position 48; and asubstitution of threonine (T) by serine (S) at position 51 utilizing theKabat numbering system
 3. An antibody, or antigen-binding fragmentthereof, of claim 2 comprising a heavy chain variable region having anamino acid sequence set forth as SEQ ID NO: 88, 89, 90, 91 or 92; and alight chain variable region having an amino acid sequence set forth asSEQ ID NO: 93, 94, 95, 96, 97, 100, 102, or
 103. 4. An antigen-bindingfragment of claim 1 wherein the antigen-binding fragment is a Fabfragment, a Fab′ fragment, a F(ab′)2 fragment, an Fv fragment, an scFvfragment, a single chain binding polypeptide, a Fd fragment, a variableheavy chain, a variable light chain or a dAb fragment.
 5. A compositioncomprising an antibody or antigen-binding fragment of claim 1, and anacceptable carrier or excipient.
 6. A nucleic acid comprising anucleotide sequence encoding an antibody or antigen-binding fragment ofclaim
 1. 7. An antibody or antigen-binding fragment thereof, of claim 1,further labeled with a therapeutic label, a diagnostic label, or both.8. A method of treating an angiogenesis-related disease in a subjectcomprising administering a composition of an antibody or antigen-bindingfragment thereof, of claim
 1. 9. The method of claim 8, wherein saidantibody or antigen-binding fragment thereof is labeled with atherapeutic label, a detectable label or both.
 10. The method of claim8, wherein the angiogenesis-related disease is an ocular diseasecharacterized by angiogenesis/neovascularization, diabetic nephropathy,IBD, rheumatoid arthritis, osteoarthritis, a cancer, or a metastasis.11. The method of claim 10, wherein the ocular disease is maculardegeneration.
 12. The method of claim 10, wherein the ocular disease isdiabetic retinopathy.
 13. The method of claim 10, wherein the cancer isa solid tumor.
 14. The method of claim 10, wherein the cancer is anepithelial based tumor
 15. The method of claim 10, wherein the cancer isselected from a lung cancer, a gynecologic malignancy, a melanoma, abreast cancer, a pancreatic cancer, an ovarian cancer, a uterine cancer,a colorectal cancer, a prostate cancer, a kidney cancer, a head cancer,a pancreatic cancer, a liver cancer (hepatocellular cancer), a uterinecancer, a neck cancer, a kidney cancer (renal cell cancer), a sarcoma, amyeloma, and a lymphoma.
 16. The method of claim 8, further comprisingadministering one or more angiogenesis inhibitors.
 17. The method ofclaim 16, wherein the angiogenesis inhibitor is chemotherapy, a VEGFreceptor inhibitor, a VEGF inhibitor, or a combination thereof.
 18. Themethod of claim 8 wherein the composition of an antibody orantigen-binding fragment thereof is administered in an amount of about0.01 mg/kg, about 0.05 mg/kg, about 0.1 mg/kg, about 0.5 mg/kg, about 1mg/kg, about 5 mg/kg, about 10 mg/kg, about 20 mg/kg, about 30 mg/kg,about 40 mg/kg, about 50 mg/kg, about 60 mg/kg, about 70 mg/kg, about 80mg/kg, about 90 mg/kg, about 100 mg/kg, about 125 mg/kg, about 150mg/kg, about 175 mg/kg, or about 200 mg/kg.
 19. A diagnostic methodcomprising: a) providing a sample of cancer cells of a solid tumor orplasma from a patient to be tested; b) detecting in the sample theexpression of at least one gene or gene product chosen from a panel ofgenes or gene products whose expression has been correlated withsensitivity or resistance to an angiogenesis inhibitor, wherein the atleast one gene or gene product is chosen from one or more genes or geneproducts selected from the group consisting of VEGF, VEGF receptor,HIF-1α, placental growth factor receptor, and CD105; and c) comparingthe level of expression of at least one gene or gene product detected inthe patient sample to a level of expression of at least one gene or geneproduct that has been correlated with sensitivity or resistance to theangiogenesis inhibitor.
 20. The method of claim 19, wherein theangiogenesis inhibitor is chosen from VEGF receptor inhibitors, VEGFinhibitors, and endoglin inhibitors.
 21. A kit comprising reagents forthe detection of expression levels that have been correlated withsensitivity or resistance to an angiogenesis inhibitor of one or moregenes selected from VEGF, VEGF receptor, HIF-1α, placental growth factorreceptor, and endoglin in a sample of cancer cells or human plasma. 22.The kit of claim 21, wherein said kit contains an antibody orantigen-binding fragment thereof.